I did wonder about that - though, if course, that implies that the CLR command does not properly clear the database. I assume it is an SQL database; not something I am (or rather, was, as it's some four years now since I did any coding, and the system we had which used it I didn't work on much) familiar with; presumably one could check it after it has been cleared.
With you on WMA, though I have only ever used the lossless version, but I did have some oddities with the Composer tag which might be releated to this; it's also possible there was - but no more - a bug in the tag editor I use, Tag&Rename, which caused both these anomalies.
Library catalogues hold their bib records in multi-level tags; most cataloguing programmes allow you to update these via a GUI, but also allow you to see the raw data. Would be good if either Tag&Rename, or indeed, MM, had this as an option
Sorted now, but these things are intensely frustrating! Inquiring minds, and all that...
If you fancy a look at tagging in Cataloguing, check out
http://www.loc.gov/marc/bibliographic/.
Here's a sample for your delectation
Leader 01041cam 2200265 a 4500
Control No. 001 ###89048230
Control No. ID 003 DLC
DTLT 005 19911106082810.9
Fixed Data 008 891101s1990 maua j 001 0 eng
LCCN 010 ## $a ###89048230
ISBN 020 ## $a 0316107514 :
$c $12.95
ISBN 020 ## $a 0316107506 (pbk.) :
$c $5.95 ($6.95 Can.)
Cat. Source 040 ## $a DLC
$c DLC
$d DLC
LC Call No. 050 00 $a GV943.25
$b .B74 1990
Dewey No. 082 00 $a 796.334/2
$2 20
ME:Pers Name 100 1# $a Brenner, Richard J.,
$d 1941-
Title 245 10 $a Make the team.
$p Soccer :
$b a heads up guide to super soccer! /
$c Richard J. Brenner.
Variant Title 246 30 $a Heads up guide to super soccer
Edition 250 ## $a 1st ed.
Publication 260 ## $a Boston :
$b Little, Brown,
$c c1990.
Phys Desc 300 ## $a 127 p. :
$b ill. ;
$c 19 cm.
Note: General 500 ## $a "A Sports illustrated for kids
book."
Note: Summary 520 ## $a Instructions for improving soccer
skills. Discusses dribbling, heading,
playmaking, defense, conditioning,
mental attitude, how to handle
problems with coaches, parents,
and other players, and the history
of soccer.
Subj: Topical 650 #0 $a Soccer
$v Juvenile literature.
Subj: Topical 650 #1 $a Soccer.