Here is the link to the FAQ page
http://www.xmarksthescot.com/forum/f...q#faq_faq_abbr

A 'TANK' is defined as an eight-yard, wool, hand-sewn, traditional kilt. ie., "It's built like a tank." (coined by Jimmy Carbomb c.2005)

I personally do not like the term, and therefore rarely use it, it has however become the norm on this and other kilt forums.