Filling Out the Header Data Structure

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.

<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>

OPTIONAL

This is the total length of the Header, in bytes. You must specify the unit:

    <object_length unit="byte">28800</object_length>

Note: Not having a length for a Header that shares a data file with any other data object - as the common FITS and VICAR headers do - can be rather inconvenient for software that wants to pass the header to some other software for processing. If it's easy to include it, SBN recommends that you do. Reviewers may require it in some cases, depending on their experience attempting to use the data files.

<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.