How to tell if my indexes are BTREE or HASH

[sneakyimp]

I'm reading some really exciting mysql documentation about query optimization. :glare:

this page refers repeatedly to BTREE and HASH indexes.
http://dev.mysql.com/doc/refman/4.1/en/range-access-multi-part.html

I don't see any way to specify or chech what my table indexes might be and thereby make heads or tales of the exciting query optimization reading I'm doing. Can anyone tell me how I would know which indexes I have added to my tables - BTREE or HASH?

[bastien]

straight from the manual

Storage Engine Allowable Index Types
MyISAM BTREE
InnoDB BTREE
MEMORY/HEAP HASH,BTREE