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-
- Used to designate an ASCII blank.
- ANSI
- American National Standards
Institute.
- Array
- A sequence of data values. This sequence
corresponds to the elements in a rectilinear, n-dimension matrix
( ).
- Array value
- The value of an element of an array
in a FITS file, without the application of the
associated linear transformation to derive the
physical value.
- ASCII
- American National Standard Code
for Information
[1] Interchange.
- ASCII blank
- The ASCII character for blank
which is represented by hexadecimal 20 (decimal 32).
- ASCII character
- Any
member of the 7-bit ASCII character set.
- ASCII NULL
- Hexadecimal 00.
- ASCII text
- ASCII characters
hexadecimal 20-7E.
- Basic FITS
- The FITS
structure
consisting of
the primary header followed by a single
primary data array.
- Bit
- A single binary digit.
- Byte
- An ordered sequence of eight consecutive bits treated as a single entity.
- Card image
- A sequence of 80 bytes containing
ASCII text , treated as a logical entity.
- Conforming extension
- An extension whose keywords and
organization
adhere to the requirements for conforming extensions defined
in §4.4.1 of this
standard.
- DAT
- 4mm Digital Audio Tape.
- Deprecated
- This term is used to refer to obsolete
structures that should not be used for new applications
but remain valid.
- Entry
- A single value in a table.
- Extension
- A FITS HDU
appearing after the primary HDU in a
FITS file.
- Extension name
- The identifier used to distinguish a particular
extension HDU from others of the same type, appearing as the value
of the EXTNAME
keyword.
- Extension type
- An extension format.
- Field
- A set of zero or more table entries collectively described by a
single format.
- File
- A sequence of one or more records terminated by an end-of-file
indicator appropriate to the medium.
- FITS
- Flexible Image Transport System.
- FITS file
- A file with a format that conforms to the
specifications in this document.
- FITS structure
- One of the
components of a FITS file:
the primary HDU,
the random groups records, an
extension , or, collectively,
the special records following
the last extension.
- Floating point
- A computer representation of a real number.
- Fraction
- The field of the mantissa
(or significand) of a floating point number that lies to
the right of its implied binary point.
- Group parameter value
- The
value of one of the parameters preceding a group in the random groups
structure, without the application of the
associated linear transformation.
- GSFC
- Goddard Space Flight Center.
- HDU
- Header and Data Unit. A data structure
consisting of a
header and the data the header describes. Note that an
HDU may consist entirely of a header with no data records.
- Header
- A series of card images organized within
one or more FITS
logical records that describes structures
and/or data which follow it in the FITS file.
- Heap
- A supplemental data area, currently defined to follow the table in
a binary table extension.
- IAU
- International Astronomical Union.
- IAUFWG
-
International Astronomical Union FITS Working Group.
- IUE
- International Ultraviolet Explorer.
- IEEE
- Institute of Electrical and
Electronic Engineers.
- IEEE NaN
- IEEE Not-a-Number
value.
- IEEE special values
- Floating point number byte patterns that have
a special, reserved meaning, such as
-0, ,
± underflow,
± overflow,
± denormalized,
± NaN. (See Appendix H).
- Indexed keyword
- A keyword that is
of the form of a fixed root with an appended positive integer count.
- Keyword
- The first eight bytes of a header card image.
- Logical record
- A record comprising
2880 8-bit bytes.
- Mandatory keyword
- A keyword that must
be used in all FITS files or a keyword required
in conjunction with particular FITS
structures.
- Mantissa
- Also known as
significand. The component of an IEEE floating point
number consisting of an explicit or implicit leading bit
to the left of its implied binary point and a fraction
field to the right.
- Matrix
- A data array of two or more dimensions.
- NOST
- NASA/Science Office of Standards and
Technology .
- Physical value
- The value in physical
units represented by an element
of an array and possibly derived from
the array value
using the associated, but optional, linear transformation.
- Picture element
- A single location within an array.
- Pixel
- Picture element.
- Primary data array
- The
data array contained in the primary HDU.
- Primary HDU
- The first HDU in a FITS file.
- Primary header
- The first header
in a FITS file, containing information on the
overall contents of the file as well as on the
primary data array.
- Record
- A sequence of bits treated as a single logical entity.
- Reference point
- The point along a given
coordinate axis , given in
units
of pixel number, at which a value and increment are defined.
- Repeat count
- The number of values
represented in a binary table field.
- Reserved keyword
- An optional keyword
that may be used only in the manner defined in this standard.
- Special records
- A series of 23040-bit (2880 8-bit byte) records,
following the primary HDU,
whose internal structure does not otherwise conform to that for
the primary HDU or to that specified for a conforming
extension in
this standard.
- Standard extension
- A
conforming
extension
whose header and data
content are specified explicitly in this standard.
- Type name
- The value of the XTENSION
keyword , used to identify
the type of the extension
in the data following.
- Valid value
- A member of a data array or table corresponding to an
actual physical quantity.
Next: 4 FITS File Organization
Up: Definition of the Flexible
Previous: 2 References
5/13/1999