git - ORIG_HEAD, FETCH_HEAD, MERGE_HEAD etc -

there's lot of useful git references (what exact name this?), e.g. head, orig_head, fetch_head, merge_head, @{upstream} etc.

is there reference this? complete list explanations?

git revisions brings http://git-scm.com/docs/gitrevisions, describes all the common ways reference commits:

• head names commit on based changes in working tree.
• fetch_head records branch fetched remote repository last git fetch invocation.
• orig_head created commands move head in drastic way, record position of head before operation, can change tip of branch state before ran them.
• merge_head records commit(s) merging branch when run git merge.
• cherry_pick_head records commit cherry-picking when run git cherry-pick.

from git source, can find out bisect_head, revert_head, reject_non_ff_head , several others never need.

that reference explains suffixes (^n, ~n, @{...}), ranges (.. vs ...), , more.