[OPEN-ILS-DEV] Cat: Maintain 001/003/035 according to the MARC21 specification

[Whalen, Liam]

I am making some modifications to 035 tags in our records, and if I do
not have the Global Flag (Cat: Maintain 001/003/035 according to the
MARC21 specification) turned off, Evergreen will add a second 035 entry
to my record when I do my SQL update to change the 035 tags.  This is
not an issue, we can turn off the flag while these updates are
proceeding.

However, if we turn the flag back on after the updates are complete will
Evergreen try to modify these records again when they are interacted
with at a later date?

Currently this is what an 035 looks like in our records.

035 $a (NRCAN-RNCAN)########  

(where ####### is our bib id).

I am updating it to look like this:

035 $a (CaOOM)#######.

I'm changing NRCAN-RNCAN to our various ILL codes.  However when I do
the SQL update with the previously mentioned Global Flag enabled, I get
a second 035 entry that looks like this:

035 $a ()########.

I have disabled the flag, proceeded with updating a single record, then
enabled the flag and edited the record manually (I have manually edited
the record two times-- once in an unrelated field and once in the 035
field) to see if the 035 $a () ####### entry would be added after
manually editing the MARC.  The empty 035 was not added, but I do not
understand how the 'Cat: Maintain 001/003/035 according to the MARC21
specification' Global Flag operates, so I'm wondering if anyone can see
any dangers in turning off the flag, doing the update, then turning the
flag back on again?

Liam