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Proposal 3: To allow additional characters in keyword names

Definition

In addition to the digits 0 through 9, the uppercase Latin alphabetic characters `A' through `Z', and the underscore and the hyphen characters, the following set of ASCII characters are allowed in FITS keyword names:

• the 'period' or 'full stop' character: '.' (ASCII decimal code 46)
• the dollar sign character: '$' (ASCII decimal code 36)
• the lowercase Latin alphabetic characters 'a' through 'z' (ASCII decimal codes 97 through 122)

Discussion

Keyword names shall be interpreted as case-insensitive. Software should preserve the case of the keyword names when displaying or copying keywords, however, any searches or comparisons that are performed on the names should behave as if any lowercase characters are first converted into uppercase.

All the mandatory and reserved keywords that are defined in the FITS Standard must always be represented as shown, with only uppercase characters.