Difference between revisions of "Filling Out the Header Data Structure"
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== <object_length> == | == <object_length> == | ||
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This is the total length of the ''Header'', in bytes. You must specify the unit: | This is the total length of the ''Header'', in bytes. You must specify the unit: | ||
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<object_length unit="byte">28800</object_length> | <object_length unit="byte">28800</object_length> | ||
</pre> | </pre> | ||
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== <parsing_standard_id> == | == <parsing_standard_id> == |
Revision as of 20:58, 28 April 2015
The <Header> class is used to provide a brief description of a header associated with some other PDS data object. The header (or it could be a footer) must be a contiguous string of bytes, and must be described by an specific standard approved for use in the PDS4 archives (FITS and VICAR are common examples).
For additional explanation, see the PDS4 Standards Reference, or contact you PDS node consultant.
Following are the attributes you'll find in <Header>, in label order.
Contents
<name>
OPTIONAL
If you want to give the Header a distinguishable, human-readable name, this is the place.
<local_identifier>
OPTIONAL
If you need to be able to refer to this Header from elsewhere in the label, assign it a unique identifier using this attribute. If your value would make a simple variable name in a typical programming language, you should be OK syntactically.
<offset>
REQUIRED
Offset in bytes from the start of the file containing the Header to the byte where the actual Header content starts. You must specify the unit:
<offset unit="byte">0</offset>
<object_length>
REQUIRED
This is the total length of the Header, in bytes. You must specify the unit:
<object_length unit="byte">28800</object_length>
<parsing_standard_id>
REQUIRED
This should contain the appropriate standard value found in the data dictionary, and also available from the Standard Values Quick Reference on this wiki.
For SBN users, the correct answer for all FITS headers (primary and extension) is "FITS 3.0".
<description>
OPTIONAL
This is a place for free-format comments and additional description.