df -k and df -m both work but only df -k is mentioned as part of df -- help. So, the omission to document -m is IMO a bug.
A second issue: Since df supports -k and -m, shouldn't if support -g (as synoym for -- block-size=1M as well? Btw. df --version outputs: df (GNU coreutils) 8.16 Andreas -- Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn,Jennifer Guild,Felix Imendörffer,HRB16746 (AG Nürnberg) GPG fingerprint = 93A3 365E CE47 B889 DF7F FED1 389A 563C C272 A126