These checksum files combine multiple level-1b md5 checksums grouped by
WISE scan id.

e.g. to check md5 checksums at NERSC:

cd /global/homes/c/cosmo/cosmo/data/wise/merge/merge_p1bm_frm
md5sum -c /project/projectdirs/cosmo/data/wise/checksums/level1b/02244a.md5
md5sum -c /project/projectdirs/cosmo/data/wise/checksums/level1b/*.md5

[Probably prints more than you actually want; need to wrap a script around
this to be very useful]