The default match for OCLC numbers in the 035 is quite strict:
pattern_map.oclc_num.pattern_0 = \\(OCoLC\\)[^0-9]**([0-9]+)=>$1
The OCLC symbol must be exactly matched. We've noticed that a significant percentage of our record imported from other sources have case errors in the OCLC symbol. Out of 6499877 fields we have these mismatches:
So about one out of every 65 OCLC numbers was not being indexed, and it's a bit much for a data cleanup. So I've made the pattern case-insensitive for our local implementation:
# Allow for case variations of OCoLC
pattern_map.oclc_num.pattern_0 = \\([Oo][Cc][Oo][Ll][Cc]\\)[^0-9]**([0-9]+)=>$1
Seems like other sites might also have similar data issues, so I mention it in case others find it relevant. Might even be worth changing in the trunk.
> Seems like other sites might also have similar data issues, so I mention it in
> case others find it relevant. Might even be worth changing in the trunk.
I've just pushed this into master -- I agree that it makes sense to be case-insensitive by default; I see no harm in doing so.