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5.1 Registered Extension Type Names

 Extension type names must be unique; a particular type name may refer to only one structure. In order to avoid duplication, all extension type names must be registered with the IAU FITS Working Group, even if the extension type is being used by only a single organization internally. To register a FITS extension name, contact either the FITS Support Office at or the chair of the IAUFWG at Provide a short description and justification with the request for registration. Reserve extension type names when their use is planned, even though details of the structure have not been worked out.

Table 5.1 lists the FITS extension type names and their registered status with the IAUFWG at the time this Guide is being written. Also included in the table are the organization with current responsibility for the extension and its development and, when available, a reference describing the extension. Table 5.2 explains the status codes in Table 5.1.

The up-to-date official listing of extensions registered with the IAUFWG is available on-line from the FITS Support Office at or This listing is revised as information is received from the IAUFWG about the registration of new type names or progress of a particular extension type through the approval process.

Table 5.1: Reserved Extension Type Names
Type Name Status Reference Sponsor Comments
'A3DTABLE' L NRAO (1990) NRAO Prototype binary table design supported in AIPS, superseded by BINTABLE, which supports all A3DTABLE features.
'BINTABLE' S Cotton, Tody, and Pence(1995) IAU Binary Tables. Available at FITS Archives in file documents/standards/bintable* for 1995-Feb-06 Note: only maindocument, excluding appendixes.
'COMPRESS' R Warnock et. al. (1990) GSFCA/ WWW Suggested name by A. Warnock Preliminary proposal
'DUMP' R none none Suggested name for binary dumps. No full proposal submitted.
'FILEMARK' R none NRAO Intended for structure to represent equivalent of tape mark on other media. No full proposal submitted.
'IMAGE ' S Ponz, Thompson, and Muñoz(1994) IAU Image extension, contains an array of one or more dimensions.
'IUEIMAGE' L Muñoz (1989) IUE Prototype matrix extension used for archiving IUE products, superseded by IMAGE.
'TABLE ' S Harten et al. (1988) IAU ASCII tables.
'VGROUP ' R Jennings et al. (1996) GSFC Reserved for possible use in supporting analog of HDF group structures under FITS. Current proposal does not use separate extension type.

Table 5.2: Possible Status Levels for FITS Extensions
Status Description
S Standard FITS extension type accepted by the IAUFWG and endorsed by the IAU.
P Proposal for FITS extension type accepted by regional FITS committees but not yet by the IAUFWG.
D Draft proposal, to be discussed in regional FITS committees and by community.
R Reserved FITS extension type name for which a full draft proposal has not yet been submitted.
L Local FITS extension type in use only by a particular group.


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Next: Conventions for Binary Tables Up: Advanced FITS Previous: Advanced FITS