MARC Global: Data Occ problem

In recent versions, the behavior of this option has been somewhat erratic. The default setting for this in MARC GLobal is 'First', and yet, it many cases, a review that contained a regular expression would not work consistently unless the option was set to 'All'.

The fix for this is quite simple. The Data Occ option will now be disabled when the regular expression option is selected. PCRE has its own mechanism for dealing with repetition in a pattern, and so, if there is a need to specify a particular occurrence of a pattern to be replaced, then that specification should be performed in the regular expression itself¹⁾.

A good thing about this fix is that it requires no changes to saved reviews. Now, when you load a 'Change Data' review that contains a regular expression, the program will turn off any code that references the Data Occurrence parameter in the saved review.