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SECTION 7. STANDARD EXTENSIONS

Table 7.3.

Valid TFORMn format values in TABLE extensions.

Field Value

Data Type

Character

Decimal integer

Floating-point, fixed decimal notation

Fw.d

Floating-point, exponential notation

Ew.d

Floating-point, exponential notation

Dw.d

Note. -- w is the width in characters of the field and

d is the number of digits to the right of the decimal.

7.2.2

Other Reserved Keywords

In addition to the reserved keywords defined in §4.4.2 (except for EXTEND and BLOCKED),

the following other reserved keywords may be used to describe the structure of an ASCII

table data array. They are optional, but if they appear within an ASCII table extension

header, they must be used as defined in this section of this standard.

TTYPEn Keywords The value field for this indexed keyword shall contain a character

string giving the name of field n. It is strongly recommended that every field of the table

be assigned a unique, case-insensitive name with this keyword, and it is recommended

that the character string be composed only of upper and lower case letters, digits, and

the underscore (`_', decimal 95, hexadecimal 5F) character. Use of other characters is

not recommended because it may be difficult to map the column names into variables in

some languages (e.g., any hyphens, `*' or `+' characters in the name may be confused

with mathematical operators). String comparisons with the TTYPEn keyword values

should not be case sensitive (e.g., 'TIME' and 'Time' should be interpreted as the same

name).

TUNITn Keywords The value field shall contain a character string describing the

physical units in which the quantity in field n, after any application of TSCALn and

TZEROn, is expressed. Units must follow the prescriptions in §4.3.

TSCALn Keywords This indexed keyword shall be used, along with the TZEROn key-

word, to linearly scale the values in the table field n to transform them into the physical

values that they represent using Eq. 7.1. The value field shall contain a floating-point

FITS Standard