Which ASCII characters are forbidden for use in SGML attributes?
-
15-03-2021 - |
Domanda
Apart from whitespace, quotation mark, equal sign, and tab, which other characters of the printable subset of ASCII are forbidden to be used as attribute names in SGML?
Soluzione
By default, SGML allows only alphanumeric values for SGML names. What additional characters are allowed for SGML names is controlled by the SGML declaration; specifically UCNMCHAR
and LCNMCHAR
under NAMING
.
For example, if you look at the SGML declaration for HTML 4, you'll see:
LCNMCHAR ".-_:"
UCNMCHAR ".-_:"
This means that the characters .
, -
, _
, and :
are also allowed in SGML names (element/attribute/entity/etc).
NOTE: Only a letter is allowed as the first character of an SGML name.
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