[osis-core] OSIS work regex

[Harry Plantinga]

If schema RegExps behave as they do in Perl, the ? is superfluous.
Perhaps

  [\L\N][\.\L\N]* 

The underscore character (_) is pretty commonly used in names and may be
present in documents converted to OSIS. I can't see that it would do any
harm. Could it be included?  Perhaps 

 [\L\N_][\.\L\N_]*

-Harry

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For the work portion:

<xs:pattern value = "([\L\N\.]([\L\N\.]*)?)" />

By which I am trying to say, any letter or number combination, followed 
by a period is complusory, followed by any number of optional 
letter/number combinations that also end in a period (periods, hyphens, 
etc., being excluded from the work name).