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25.2 Interface conventions

The following conventions hold:

In the procedure specifications:

An argument followed by ... means zero–or–more elements. So the procedure with the signature:

sum-squares x ...

takes zero or more arguments (x, …), while the procedure with signature:

spell-check doc dict1 dict2 ...

takes two mandatory arguments (doc and dict1) and zero or more optional arguments (dict2 ...).

If a procedure is said to return “unspecified”, this means that nothing at all is known about what the procedure returns. Such a procedure is not even required to be consistent from call to call. It is simply required to return a value (or values) that may be passed to a command continuation, e.g. as the value of an expression appearing as a non–terminal subform of a begin expression.

Comparison is simply done on individual code–points of the string. Unless explicitly stated, for all the functions: Case–insensitive comparison is done using the functions:

char-ci=? char-ci<? char-ci>? char-ci<=? char-ci>=?

provided by the underlying implementation, or by case–folding characters with the operation:

(char-downcase (char-upcase c))

where the two case–mapping operations are assumed to be one–to–one, locale–insensitive and context–insensitive, and compatible with the one–to–one case mappings specified by Unicode’s UnicodeData.txt table:

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