For this plugin TC shows these units for field "size": bytes, kbytes, Mbytes, Gbytes, bkM, bkM2.Filesys sample plugin:
It does the same as the (int) built-in content plugin
Author: Christian Ghisler
But I tested this plugin with WDX Guide: it has only units: bytes, kbytes, Mbytes, Gbytes.
This is maybe a TC bug: from where it gets units "bkM, bkM2"?
And if you look into .wdx file, you'll see string "bytes|kbytes|Mbytes|Gbytes", without "bmM|bkM2"...