Somewhere in the middle of that doc it says that PATTERN can be
a string composed of a single space character (such as ' ' or "\x20" , but not e.g. / / ).
However, the only PATTERN strings that I find there are whitespace (PATTERN defaults to " " if omitted) and the empty string.

In reply to Re^4: Matching dot using regexp by soonix
in thread Matching dot using regexp by Anonymous Monk

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