### Install CRDS and Dependencies (File Submission)

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

Installs CRDS and its dependencies for file submission roles. This involves cloning the CRDS repository and running a setup script. It's recommended to do this in a dedicated environment.

```bash
git clone https://github.com/spacetelescope/crds.git
cd crds
./crds_setup_crds
```

--------------------------------

### Customize CRDS Environment Setup

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

Demonstrates how to customize the CRDS environment setup by specifying OS, shell, and install location. This allows for more flexible installation configurations.

```bash
./crds_setup_all   Linux  csh   $HOME/miniconda_crds
```

--------------------------------

### Install CRDS and Dependencies (Full Environment)

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

Installs a complete environment including a baseline conda, CRDS, and all its dependencies. This is useful for starting from scratch or setting up a dedicated environment for CRDS development and usage.

```bash
git clone https://github.com/spacetelescope/crds.git
cd crds
./crds_setup_all

# open a new terminal window
conda activate crds-env
```

--------------------------------

### Check CRDS Version

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/installation.rst

A command-line instruction to check the installed version of the CRDS client software. This is a basic verification step.

```Shell
crds list --version
```

--------------------------------

### Install Full Featured CRDS with Development Dependencies

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

Installs the latest CRDS from GitHub with a comprehensive set of dependencies, including those for submission, development, testing, and documentation. This is the most complete installation for users actively developing or testing CRDS.

```bash
pip install --upgrade  git+https://github.com/spacetelescope/crds.git#egg=crds["submission","dev","test","docs"]
```

--------------------------------

### CRDS Submission Logging Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/programmatic_interface.rst

Illustrates the logging output during the CRDS submission process, showing steps like setup, context resolution, file certification, and conformance checks.

```APIDOC
2019-04-24 12:24:50,823 - CRDS - INFO -  =============================== setting up ===============================
2019-04-24 12:24:51,038 - CRDS - INFO -  Symbolic context 'jwst-edit' resolves to 'jwst_0511.pmap'
2019-04-24 12:24:51,038 - CRDS - INFO -  ########################################
2019-04-24 12:24:51,038 - CRDS - INFO -  Certifying './miri_dark_test.fits' (1/1) as 'FITS' relative to context 'jwst_0511.pmap'
2019-04-24 12:24:55,166 - CRDS - INFO -  FITS file 'miri_dark_test.fits' conforms to FITS standards.
2019-04-24 12:24:56,219 - CRDS - WARNING -  Missing suggested keyword 'META.MODEL_TYPE [DATAMODL]'
```

--------------------------------

### CRDS Certify: Usage Examples

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Provides practical examples of how to use the `crds.certify` command with different options for validating FITS files and mapping files.

```bash
$ crds certify --comparison-context=hst_0027.pmap --run-fitsverify --dump-provenance ./some_reference.fits
```

```bash
$ crds certify ./hst_acs_darkfile_00250.rmap
```

--------------------------------

### Install Latest CRDS with Submission and Test Dependencies

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

Uninstalls any existing CRDS installation and installs the latest version from GitHub, including dependencies for submission and testing roles. This is a more advanced installation for users needing specific CRDS features.

```bash
pip uninstall --yes crds
pip install --upgrade  git+https://github.com/spacetelescope/crds.git#egg=crds["submission","test"]
```

--------------------------------

### Install JWST Software and Dependencies

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

Installs the JWST calibration software and related dependencies, including numpy and the latest CRDS from GitHub. Note that this might install a CRDS version that is not current enough for specific testing needs.

```bash
pip install --upgrade numpy
pip install --upgrade git+https://github.com/spacetelescope/jwst
```

--------------------------------

### Check CRDS Installation and Configuration

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

This command checks the current installation status of CRDS, displaying version information, mode, paths, cache status, and the effective context. It's useful for verifying a successful installation and understanding the current CRDS environment.

```bash
crds list --status
```

--------------------------------

### Setup Offsite Use for Roman

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/basic_use.rst

Sets up CRDS for offsite Roman calibration by defining CRDS_PATH and CRDS_SERVER_URL environment variables before running the pipeline.

```bash
$ export CRDS_SERVER_URL=https://roman-crds.stsci.edu   # or similar
$ export CRDS_PATH=${HOME}/crds_cache
$ strun roman_elp dataset.asdf
```

--------------------------------

### CRDS Parameter Combinations Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/file_submissions.rst

Illustrates how different parameter combinations like DETECTOR, CCDAMP, and CCDGAIN are used to define support for specific data files. The example shows a mapping of date ranges to dark frame fits files for the HRC detector.

```Python
DETECTOR  CCDAMP              CCDGAIN

('HRC', 'A|ABCD|AD|B|BC|C|D', '1.0|2.0|4.0|8.0') : UseAfter({
  '1992-01-01 00:00:00' : 'lcb12060j_drk.fits',
  '2002-03-01 00:00:00' : 'n3o1022cj_drk.fits',
  '2002-03-18 00:00:00' : 'n3o1022ej_drk.fits',
  '2002-03-19 00:34:31' : 'n3o1022fj_drk.fits',
  '2002-03-20 00:34:32' : 'n3o1022hj_drk.fits',
  ...
})
```

--------------------------------

### Get System Versions (JSONRPC API)

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Shows how to make a POST request to the CRDS JSONRPC endpoint to retrieve system versions. This example includes a successful response with detailed version information.

```bash
$ curl -i -X POST -d '{"jsonrpc": "1.0", "method": "get_system_versions", "params": ["0.6.0noop.dev307","null"], "id": 1}  ' https://jwst-crds-dit.stsci.edu/json/
HTTP/1.1 200 OK
Date: Wed, 24 Aug 2016 22:33:04 GMT
Vary: Cookie
X-Frame-Options: SAMEORIGIN
Content-Type: application/json-rpc
Via: 1.1 jwst-crds-dit.stsci.edu
Transfer-Encoding: chunked

{"error": null, "jsonrpc": "1.0", "id": 1, "result": {"reftype": "CALVER", "author": "Warren J. Hack", "versions":   {"TweakRegStep": "0.1.0", "SubtractImagesStep": null, "RSCD_Step": null, "CubeBuildStep": null, "Extract1dStep": null,   "AmiAnalyzeStep": "0.7.0.dev", "Extract2dStep": null, "BackgroundStep": null, "SuperBiasStep": null, "DarkCurrentStep":   null, "Combine1dStep": null, "SaturationStep": null, "LinearityStep": null, "DQInitStep": null, "ImprintStep": null,   "OutlierDetectionStep": null, "AssignWcsStep": null, "KlipStep": null, "StackRefsStep": null, "TweakregCatalogStep":   null, "SourceCatalogStep": null, "PersistenceStep": null, "StraylightStep": null, "IPCStep": null, "FlatFieldStep":   null, "ResetStep": null, "RefPixStep": null, "ResampleStep": null, "AmiAverageStep": "0.7.0.dev", "FringeStep": null,   "AlignRefsStep": null, "LastFrameStep": null, "JumpStep": null, "EmissionStep": null, "WfsCombineStep": null,   "AmiNormalizeStep": "0.7.0.dev", "SkyMatchStep": "0.1.0", "PhotomStep": null, "RampFitStep": null, "HlspStep": null},   "instrument": "SYSTEM", "descrip": "JWST calibration processing step version reference file", "CAL_VER": "0.6.0noop.  dev307", "history": "Created by cal_ver_steps version 0.7.0.dev"}}
```

--------------------------------

### Setup Offsite Use for JWST

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/basic_use.rst

Sets up CRDS for offsite JWST calibration by defining CRDS_PATH and CRDS_SERVER_URL environment variables before running the pipeline.

```bash
$ export CRDS_SERVER_URL=https://jwst-crds.stsci.edu   # or similar
$ export CRDS_PATH=${HOME}/crds_cache
$ strun calwebb_sloper.cfg dataset.fits
```

--------------------------------

### Install Fitsverify with Conda

Source: https://github.com/spacetelescope/crds/blob/master/README.rst

Installs the Fitsverify package using conda from the astroconda channel. This is a C-based package not available via pip.

```bash
conda config --add channels http://ssb.stsci.edu/astroconda
conda install --yes fitsverify
```

--------------------------------

### Roman WFI FLAT Reference Mapping Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

An example of a reference mapping file (.rmap) for the Roman WFI FLAT. It includes header metadata and a selector that uses `Match` and `UseAfter` to choose flat field files based on detector and optical element.

```Bash
header = {
    'classes' : ('Match', 'UseAfter'),
    'derived_from' : 'roman_wfi_flat_0002.rmap',
    'file_ext' : '.asdf',
    'filekind' : 'FLAT',
    'filetype' : 'FLAT',
    'instrument' : 'WFI',
    'ld_tpn' : 'wfi_flat_ld.tpn',
    'mapping' : 'REFERENCE',
    'name' : 'roman_wfi_flat_0002.rmap',
    'observatory' : 'ROMAN',
    'parkey' : (('META.INSTRUMENT.DETECTOR', 'META.INSTRUMENT.OPTICAL_ELEMENT'), ('META.OBSERVATION.DATE', 'META.OBSERVATION.TIME')),
    'sha1sum' : 'bf0119bfbe1d8e5010eb3bec87bc45d575ae8313',
    'suffix' : 'flat',
    'text_descr' : 'Flat Field',
    'tpn' : 'wfi_flat.tpn',
}

selector = Match({
    ('WFI01', 'F158') : UseAfter({
        '2020-01-01 00:00:00' : 'roman_wfi_flat_0001.asdf',
    }),
})
```

--------------------------------

### JWST Header Examples for get_best_references

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Provides example JSON structures for the `header` parameter when using the `get_best_references` function for JWST data. It shows how to specify instrument type, detector, and filter using both data model dotted identifiers and equivalent FITS header keywords.

```python
{"meta.instrument.type":"fgs", 
 "meta.instrument.detector":"fgs1", 
 "meta.instrument.filter":"any"}
```

```python
{"instrume":"fgs", 
 "detector":"fgs1", 
 "filter":"any"}
```

--------------------------------

### CRDS Master Program Help

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Displays the usage information for the main 'crds' command-line tool, outlining its structure as a wrapper for various CRDS sub-commands and providing an example of assigning HST best reference files.

```bash
$ crds --help

usage: crds <command> <parameters...>

'crds' is a wrapper used to invoke various CRDS sub-programs.

For example, to assign HST best reference files, do:

    $ crds bestrefs --files *.fits  --update-bestrefs

Available commands:

list                -- print information about CRDS configuration, etc. 
certify             -- check CRDS reference and rules files
bestrefs            -- assign bestrefs to datasets, regressions, repro
sync                -- manage local CRDS cache, download rules + references
diff                -- difference CRDS rules and references
rowdiff             -- difference reference tables
matches             -- list matching criteria relative to particular rules
checksum            -- update rmap checksum
query_affected      -- download CRDS new reference files affected dataset IDs
uniqname            -- rename HST files with new CDBS-style names
get_synphot         -- download synphot references
newcontext          -- automatically generates updated imaps and pmaps
refactor            -- automatically modifies rmaps

For more detail about individual commands use --help:

e.g. crds list --help
```

--------------------------------

### CRDS JSONRPC get_best_references Example (FITS Parkey)

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Demonstrates calling the 'get_best_references' method with FITS parkey names using a Python-like syntax, showing the request and response.

```python
>>> jsonrpc.get_best_references("jwst_0000.pmap", {'INSTRUME':'FGS','DETECTOR':'FGS1', 'FILTER':'ANY'}, null)
Requesting ->
{"id":"jsonrpc", "params":["jwst_0000.pmap", {"INSTRUME":"FGS", "DETECTOR":"FGS1", "FILTER":"ANY"}, null], "method":"get_best_references", "jsonrpc":"1.0"}
Deferred(12, unfired)
Got ->
{"error": null, "jsonrpc": "1.0", "id": "jsonrpc", "result": {"linearity": "jwst_fgs_linearity_0000.fits", "amplifier": "jwst_fgs_amplifier_0000.fits", "mask": "jwst_fgs_mask_0000.fits"}}
```

--------------------------------

### ROMAN Pipeline Mapping (.pmap) Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

This Python code provides an example of a ROMAN pipeline mapping file, including its header and selector. The header specifies observatory details and the parkey, while the selector maps the WFI instrument to its corresponding instrument mapping file.

```python
header = {
    'derived_from' : 'roman_0036.pmap',
    'description' : 'Updated parkey to include roman prefix.',
    'mapping' : 'PIPELINE',
    'name' : 'roman_0037.pmap',
    'observatory' : 'ROMAN',
    'parkey' : ('ROMAN.META.INSTRUMENT.NAME',),
    'sha1sum' : '7765a10e18b1607ba268c62033f38130bb995690',
}

selector = {
    'WFI' : 'roman_wfi_0035.imap',
}
```

--------------------------------

### Setup Offsite Use for HST

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/basic_use.rst

Configures CRDS for offsite use by setting the CRDS_SERVER_URL and CRDS_PATH environment variables, and then synchronizes references for specified FITS datasets.

```bash
$ export CRDS_SERVER_URL=https://hst-crds.stsci.edu   # or similar
$ export CRDS_PATH=${HOME}/crds_cache
$ crds bestrefs --files dataset*.fits --sync-references=1  --update-bestrefs
```

--------------------------------

### Roman Header Examples for get_best_references

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Provides example JSON structures for the `header` parameter when using the `get_best_references` function for Roman data. It illustrates how to specify exposure type, detector, and table number using Roman Datamodels dotted identifiers.

```python
{"roman.meta.exposure.type":"grism", 
 "roman.meta.instrument.detector":"wfi01", 
 "roman.meta.exposure.ma_table_number":"any"}
```

--------------------------------

### Array Name Specification Examples

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/certify_constraints.rst

Illustrates how array names are specified in CRDS, including references to FITS extensions by number and by (name, ver) pair.

```Python
Array names are specified as the bare HDU name in the <name> field, e.g. SCI.
These are referenced within expressions as <name>_ARRAY. 

1. FITS extensions can also named by number, e.g.  EXT1 or EXTENSION1 refers to
   the data of HDU #1.  In constraint expressions these are referred to as
   e.g. EXT1_ARRAY.

2. FITS extensions can be named by (name, ver), in CRDS this is denoted as
   <name>__<ver>, which corresponds to e.g. ('SCI', 1).  In constraint
   expressions they are referred to as as <name>__<ver>_ARRAY,
   e.g. SCI__1_ARRAY.
```

--------------------------------

### CRDS JSONRPC get_best_references Example (JWST Parkey)

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Demonstrates calling the 'get_best_references' method with JWST data model parkey names using a Python-like syntax, showing the request and response.

```python
>>> jsonrpc.get_best_references("jwst_0000.pmap", {'META.INSTRUMENT.TYPE':'FGS','META.INSTRUMENT.DETECTOR':'FGS1', 'META.INSTRUMENT.FILTER':'ANY'}, null)
Requesting ->
{"id":"jsonrpc", "params":["jwst_0000.pmap", {"META.INSTRUMENT.TYPE":"FGS", "META.INSTRUMENT.DETECTOR":"FGS1", "META.INSTRUMENT.FILTER":"ANY"}, null], "method":"get_best_references", "jsonrpc":"1.0"}
Deferred(14, unfired)
Got ->
{"error": null, "jsonrpc": "1.0", "id": "jsonrpc", "result": {"linearity": "jwst_fgs_linearity_0000.fits", "amplifier": "jwst_fgs_amplifier_0000.fits", "mask": "jwst_fgs_mask_0000.fits"}}
```

--------------------------------

### CRDS SelectVersion Selector Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

Shows the SelectVersion operator, which selects a reference file based on a software version and relational expressions, prioritizing versions in sorted order.

```Python
selector = SelectVersion({
   '<3.1':    'cref_flatfield_65.fits',
   '<5':      'cref_flatfield_73.fits',
   'default': 'cref_flatfield_123.fits',
})
```

--------------------------------

### CRDS Substitution Parameters Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

Demonstrates the definition and usage of substitution parameters in CRDS rmap headers to manage complex matching rules for reference files based on dataset header values.

```Python
selector = Match({
    ('UVIS', 'G280_AMPS', '1.5', '1.0', '1.0', 'G280-REF', 'T') : UseAfter({

    }),
 })

'substitutions' : {
    'CCDAMP' : {
        'G280_AMPS' : ('ABCD', 'A', 'B', 'C', 'D', 'AC', 'AD', 'BC', 'BD'),
    },
}
```

--------------------------------

### CRDS Get Recommendations

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/library_use.rst

Retrieves recommendations for best calibration references based on dataset parameters and context. It does not cache files locally. Requires network connectivity and potentially environment variables like CRDS_SERVER_URL and CRDS_PATH.

```python
def getrecommendations(parameters, reftypes=None, context=None, ignore_cache=False,
                       observatory="jwst", fast=False):
    """
    getrecommendations() returns the best references for the specified `parameters`
    and pipeline `context`.   Unlike getreferences(),  getrecommendations() does
    not attempt to cache the files locally.
        
    parameters      { str:  str,int,float,bool, ... }
    
      `parameters` should be a dictionary-like object mapping best reference 
      matching parameters to their values for this dataset.
    
    reftypes        [ str, ... ] 
    
      If `reftypes` is None,  return all possible reference types.   Otherwise
      return the reference types specified by `reftypes`.
    
    context         str
    
      Specifies the pipeline context, i.e. specific version (.pmap) of CRDS
      rules used to do the best references match.  If `context` is None, use
      the latest available context.

     ignore_cache    bool

       If `ignore_cache` is True,  download files from server even if already present.

     observatory     str

       nominally 'jwst' or 'hst'.

       fast            bool

      If fast is True, skip verbose output, parameter screening, implicit 
      config update, and bad reference checking. 

     Returns { reftype : bestref_basename, ... }

       returns a mapping from types requested in `reftypes` to the path for each 
       cached reference file.
    """
```

--------------------------------

### CRDS Warning Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/file_submissions.rst

Illustrates a warning message from CRDS indicating an 'equal weight special case' where two different match cases are considered equally good for a given parameter set.

```text
CRDS - WARNING -  ----------------------------------------
Match case
 (('DETECTOR', 'FUV'),)
is an equal weight special case of
 (('DETECTOR', 'FUV|NUV'),)
For some parameter sets, CRDS interprets both matches as equally good.
```

--------------------------------

### Roman Pattern Specification Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/reference_conventions.rst

Illustrates the pattern specification for Roman using 'P_' prefixed keywords in ASDF and datamodels paths, similar to JWST, with OR-ed values and a required trailing '|'.

```python
P_OPTICAL_ELEMENT = F213 | F158 |

roman.meta.instrument.p_optical_element = F213 | F158 |
```

--------------------------------

### CRDS JSONRPC Generic Request Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Demonstrates a generic CRDS service request using the UNIX command line utility 'curl'. It shows how to POST a JSONRPC request with method, parameters, and ID.

```bash
$ curl -i -X POST -d '{"jsonrpc": "1.0", "method": "get_default_context", "params": ["jwst"], "id": 1}' https://jwst-crds.stsci.edu/json/
```

--------------------------------

### CRDS UseAfter Selector Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

Illustrates the UseAfter selector in CRDS, which matches an ordered sequence of date-time values to corresponding reference filenames, selecting the greatest date-time less than or equal to the dataset's EXPSTART.

```Python
selector = Match({
    ('HRC',) : UseAfter({
        '1991-01-01 00:00:00' : 'j4d1435hj_a2d.fits',
        '1992-01-01 00:00:00' : 'kcb1734ij_a2d.fits',
    }),
    ('WFC',) : UseAfter({
        '1991-01-01 00:00:00' : 'kcb1734hj_a2d.fits',
        '2008-01-01 00:00:00' : 't3n1116mj_a2d.fits',
    }),
 })
```

--------------------------------

### CRDS Sync Command Examples

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/environment.rst

Demonstrates how to use the `crds sync` command to fetch test rules and references. The first command fetches all test rules, while the second (commented out) would fetch specifically listed test references.

```bash
# Fetch all the test rules
$ crds sync --all

# Fetch specifically listed test references
```

--------------------------------

### Get CRDS Context History

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Fetches the history of CRDS contexts that have been activated as the latest context in the pipeline. The history is returned as a list of tuples, each containing a start date, context name, and a description.

```python
client.get_context_history("jwst")
# Expected output format:
# [('2012-09-06 00:00:00', 'jwst.pmap', 'Bootstrap mappings'), ...]
```

--------------------------------

### Build Server Documentation

Source: https://github.com/spacetelescope/crds/blob/master/documentation/README.rst

Builds the server-side HTML documentation for the CRDS project. This command is typically executed from within the documentation directory.

```bash
$ make serverhtml
```

--------------------------------

### Get System Versions (JSONRPC API - Error Example)

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Illustrates how the CRDS JSONRPC API handles invalid input, showing a response where 'result' is null and the 'error' field contains a descriptive message.

```bash
$ curl -i -X POST -d '{"jsonrpc": "1.0", "method": "get_system_versions", "params": ["an,invalid(version)","null"],   "id": 1}' https://jwst-crds-dit.stsci.edu/json/
HTTP/1.1 200 OK
Date: Wed, 24 Aug 2016 22:23:11 GMT
Vary: Cookie
X-Frame-Options: SAMEORIGIN
Content-Type: application/json-rpc
Via: 1.1 jwst-crds-dit.stsci.edu
Transfer-Encoding: chunked


```

--------------------------------

### Get Default Context Name

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/library_use.rst

The get_default_context() function returns the name of the current pipeline mapping (context). For JWST, this is the Build Context corresponding to the installed DMS and Calibration code. For HST and Roman, it's the Latest Context from the CRDS server or local cache.

```python
def get_default_context():
    """Return the name of the latest pipeline mapping in use for processing
    files.  
    
    Returns   
    -------
    pipeline context name
    
        e.g.   'hst_0007.pmap'
    """
```

--------------------------------

### CRDS Array Data Constraint Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/certify_constraints.rst

An example of how array data constraints are structured using utils.Struct, referencing header and array properties like shape, kind, and data.

```Python
utils.Struct(
    SHAPE = hdu.data.shape,
    KIND = generic_class,
    DATA_TYPE = typespec,
    COLUMN_NAMES = column_names,
    EXTENSION = i,
    DATA = hdu.data      #  XXX the difference between 'A' and 'D' constraints!
)
```

--------------------------------

### Sync References by Context

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Downloads all references mentioned by specified contexts.

```bash
$ crds sync  --contexts hst_0001.pmap hst_0002.pmap  --fetch-references
```

--------------------------------

### Remove references to ICD-47 in users guide

Source: https://github.com/spacetelescope/crds/blob/master/CHANGES.rst

Removes outdated references to ICD-47 (Interface Control Document 47) from the user's guide, updating the documentation to reflect current standards or practices.

```Markdown
## User's Guide Updates

Removed all mentions and references to ICD-47 to ensure the documentation is current and accurate.
```

--------------------------------

### CRDS Matches Command Usage and Examples

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Details the 'crds matches' command for displaying selection criteria of reference files against CRDS contexts. Includes options for specifying contexts, files, output formatting, and dataset matching.

```bash
usage: crds matches ...
       [-h] [--contexts [CONTEXT [CONTEXT ...]]]
       [--files FILES [FILES ...]] [-b] [-o] [-t]

Prints out the selection criteria by which the specified references are matched
with respect to a particular context.

optional arguments:
  -h, --help            show this help message and exit
  --contexts [CONTEXT [CONTEXT ...]]
                        Specify a list of CRDS mappings to operate on: .pmap, .imap, or .rmap or date-based specification
  --range MIN:MAX       Operate for pipeline context ids (.pmaps) between <MIN> and <MAX>.
  --all                 Operate with respect to all known CRDS contexts.
  --last N              Operate with respect to the last N contexts.
  -i, --ignore-cache    Download required files even if they're already in the cache.
  --files FILES [FILES ...]
                        References for which to dump selection criteria.
  -b, --brief-paths     Don't the instrument and filekind.
  -o, --omit-parameter-names
                        Hide the parameter names of the selection criteria,  just show the values.
  -t, --tuple-format    Print the match info as Python tuples.
  -d DATASETS [DATASETS ...], --datasets DATASETS [DATASETS ...]
                        Dataset ids for which to dump matching parameters from DADSOPS or equivalent database.
  -c, --condition-values
                        When dumping dataset parameters, first apply CRDS value conditioning / normalization.
  -m, --minimize-header
                        When dumping dataset parameters,  limit them to matching parameters, not historical bestrefs.
  -v, --verbose         Set log verbosity to True,  nominal debug level.
  --verbosity VERBOSITY
                        Set log verbosity to a specific level: 0..100.
  -R, --readonly-cache  Don't modify the CRDS cache.  Not compatible with options which implicitly modify the cache.
  -V, --version         Print the software version and exit.
  -J, --jwst            Force observatory to JWST for determining header conventions.
  -H, --hst             Force observatory to HST for determining header conventions.
```

```bash
$ crds matches  --contexts hst_0001.pmap --files lc41311jj_pfl.fits
lc41311jj_pfl.fits : ACS PFLTFILE DETECTOR='WFC' CCDAMP='A|ABCD|AC|AD|B|BC|BD|C|D' FILTER1='F625W' FILTER2='POL0V' DATE-OBS='1997-01-01'   TIME-OBS='00:00:00'
```

```bash
$ crds matches --contexts hst.pmap --files lc41311jj_pfl.fits --omit-parameter-names --brief-paths
lc41311jj_pfl.fits :  'WFC' 'A|ABCD|AC|AD|B|BC|BD|C|D' 'F625W' 'POL0V' '1997-01-01' '00:00:00'
```

```bash
$ crds matches --contexts hst.pmap --files lc41311jj_pfl.fits --tuple-format
lc41311jj_pfl.fits : (('OBSERVATORY', 'HST'), ('INSTRUMENT', 'ACS'), ('FILEKIND', 'PFLTFILE'), ('DETECTOR', 'WFC'), ('CCDAMP', 'A|ABCD|  AC|AD|B|BC|BD|C|D'), ('FILTER1', 'F625W'), ('FILTER2', 'POL0V'), ('DATE-OBS', '1997-01-01'), ('TIME-OBS', '00:00:00'))
```

```bash
$ crds matches --datasets JBANJOF3Q --minimize-headers --contexts hst_0048.pmap hst_0044.pmap
```

--------------------------------

### CRDS Uses Command Examples

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Demonstrates how to use the 'crds uses' command to list associated CRDS mapping files (.pmap, .imap) and reference files (.rmap) for given FITS files, with options to print datasets and include used files.

```bash
$ crds uses --files n3o1022ij_drk.fits --hst
hst.pmap
hst_0001.pmap
hst_0002.pmap
hst_0003.pmap
...
hst_0041.pmap
hst_acs.imap
hst_acs_0001.imap
hst_acs_0002.imap
hst_acs_0003.imap
...
hst_acs_0008.imap
hst_acs_darkfile.rmap
hst_acs_darkfile_0001.rmap
hst_acs_darkfile_0002.rmap
hst_acs_darkfile_0003.rmap
...
hst_acs_darkfile_0005.rmap
```

```bash
$ crds uses --files n3o1022ij_drk.fits --print-datasets --hst
J8BA0HRPQ
J8BA0IRTQ
J8BA0JRWQ
J8BA0KT4Q
J8BA0LIJQ
```

```bash
$ crds uses --files @dropped --hst --print-datasets --include-used
vb41934lj_bia.fits JA7P21A2Q
vb41934lj_bia.fits JA7P21A4Q
vb41934lj_bia.fits JA7P21A6Q
```

--------------------------------

### CRDS rmap Header Configuration Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

An example of a Python dictionary representing an rmap header configuration in CRDS. It includes fields like 'parkey', 'extra_keys', 'reffile_switch', 'rmap_relevance', 'rmap_omit', and 'hooks' which control reference file lookups.

```python
header = {
    ...

    'parkey' : (('DETECTOR',), ('DATE-OBS', 'TIME-OBS')),

    'extra_keys' : ('XCORNER', 'YCORNER', 'CCDCHIP'),

    'reffile_switch' : 'BIASCORR',

    'reffile_required' : 'YES',

    'rmap_relevance' : '((DETECTOR != "SBC") and (BIASCORR != "OMIT"))',
    'rmap_omit' : '((DETECTOR != "SBC") and (BIASCORR != "OMIT")),

    'parkey_relevance' : {
        'binaxis1' : '(DETECTOR == "UVIS")',
        'binaxis2' : '(DETECTOR == "UVIS")',
        'ccdgain' : '(DETECTOR == "IR")',
        'samp_seq' : '(DETECTOR == "IR")',
        'subtype' : '(DETECTOR == "IR")',
    },

    'hooks' : {
        'fallback_header' : 'fallback_header_acs_biasfile_v2',
        'precondition_header' : 'precondition_header_acs_biasfile_v2',
    },

    ...
}
```

--------------------------------

### HST COS DEADTAB Reference Mapping Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

An example of a reference mapping file (.rmap) for the HST COS DEADTAB. It includes header information and a selector using `Match` and `UseAfter` to select deadtab files based on detector and observation date.

```Bash
header = {
    'derived_from' : 'generated from CDBS database 2014-05-09 23:24:57.840119',
    'filekind' : 'DEADTAB',
    'instrument' : 'COS',
    'mapping' : 'REFERENCE',
    'name' : 'hst_cos_deadtab_0250.rmap',
    'observatory' : 'HST',
    'parkey' : (('DETECTOR',), ('DATE-OBS', 'TIME-OBS')),
    'reffile_format' : 'TABLE',
    'reffile_required' : 'NONE',
    'reffile_switch' : 'DEADCORR',
    'rmap_relevance' : '(DEADCORR != "OMIT")',
    'sha1sum' : 'bde314f1848b67891d6309b30eaa5c95611f86e2',
}

selector = Match({
    ('FUV',) : UseAfter({
        '1996-10-01 00:00:00' : 's7g1700gl_dead.fits',
    }),
    ('NUV',) : UseAfter({
        '1996-10-01 00:00:00' : 's7g1700ql_dead.fits',
    }),
})
```

--------------------------------

### CRDS Matches Command Usage

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Demonstrates how to use the 'crds matches' command with different output formatting options, including specifying contexts, files, omitting parameter names, using brief paths, and tuple formatting.

```bash
$ crds matches  --contexts hst_0001.pmap --files lc41311jj_pfl.fits
lc41311jj_pfl.fits : ACS PFLTFILE DETECTOR='WFC' CCDAMP='A|ABCD|AC|AD|B|BC|BD|C|D' FILTER1='F625W' FILTER2='F660N' DATE-OBS='1997-01-01'   TIME-OBS='00:00:00'
```

```bash
$ crds matches --contexts hst.pmap --files lc41311jj_pfl.fits --omit-parameter-names --brief-paths
lc41311jj_pfl.fits :  'WFC' 'A|ABCD|AC|AD|B|BC|BD|C|D' 'F625W' 'POL0V' '1997-01-01' '00:00:00'
```

```bash
$ crds matches --contexts hst.pmap --files lc41311jj_pfl.fits --tuple-format
lc41311jj_pfl.fits : (('OBSERVATORY', 'HST'), ('INSTRUMENT', 'ACS'), ('FILEKIND', 'PFLTFILE'), ('DETECTOR', 'WFC'), ('CCDAMP', 'A|ABCD|  AC|AD|B|BC|BD|C|D'), ('FILTER1', 'F625W'), ('FILTER2', 'POL0V'), ('DATE-OBS', '1997-01-01'), ('TIME-OBS', '00:00:00'))
```

--------------------------------

### CRDS Sync - Observatory and File Specification

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Demonstrates how to use `crds.sync` to download CRDS data, specifying the observatory (HST, JWST, Roman) via flags or environment variables. It shows how to sync specific files and output directories.

```bash
export CRDS_SERVER_URL=https://hst-crds.stsci.edu
crds sync --files 2cd1621ei_dkc.fits --output-dir
crds.sync --hst --files 2cd1621ei_dkc.fits --output-dir
```

--------------------------------

### JWST MIRI DARK Reference Mapping Example

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/rmap_syntax.rst

An example of a reference mapping file (.rmap) for the JWST MIRI DARK. It specifies header details and uses a `Match` operator with `UseAfter` to select dark frames based on detector, filter, and read pattern.

```Bash
header = {
    'derived_from' : 'cloning tool 0.03b (2012-09-11)',
    'filekind' : 'DARK',
    'instrument' : 'MIRI',
    'mapping' : 'REFERENCE',
    'name' : 'jwst_miri_dark_0000.rmap',
    'observatory' : 'JWST',
    'parkey' : (('META.INSTRUMENT.DETECTOR', 'META.INSTRUMENT.FILTER', 'META.EXPOSURE.READPATT'),),
    'sha1sum' : '2535d3be806c6e7f5f0da1f2dce64034f9028ddc',
}

selector = Match({
    ('MIRIFULONG', 'ANY', 'FAST') : 'jwst_miri_dark_0000.fits',
    ('MIRIFULONG', 'ANY', 'SLOW') : 'jwst_miri_dark_0001.fits',
    ('MIRIFUSHORT', 'ANY', 'FAST') : 'jwst_miri_dark_0002.fits',
    ('MIRIFUSHORT', 'ANY', 'SLOW') : 'jwst_miri_dark_0003.fits',
    ('MIRIMAGE', 'ANY', 'FAST') : 'jwst_miri_dark_0004.fits',
    ('MIRIMAGE', 'ANY', 'SLOW') : 'jwst_miri_dark_0005.fits',
})
```

--------------------------------

### CRDS Parameter Loading and Saving

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/command_line_tools.rst

Demonstrates how to load and save CRDS parameters using pickle (.pkl) or JSON (.json) files. `--load-pickles` loads parameters from a sequence of files, and `--save-pickle` saves the combined results to a specified file format.

```bash
crds.bestrefs --load-pickles <file1.pkl> <file2.json> --save-pickle <output.json>
```

--------------------------------

### CRDS JSONRPC Sample URLs

Source: https://github.com/spacetelescope/crds/blob/master/documentation/crds_users_guide/source/web_services.rst

Provides sample base URLs for making CRDS JSONRPC method calls for different telescopes like HST, JWST, and ROMAN.

```bash
http://hst-crds.stsci.edu/json/
```

```bash
http://jwst-crds.stsci.edu/json/
```

```bash
http://roman-crds.stsci.edu/json/
```