-A "commit" object ties such directory hierarchies together into
-a DAG of revisions - each "commit" is associated with exactly one tree
-(the directory hierarchy at the time of the commit). In addition, a
-"commit" refers to one or more "parent" commit objects that describe the
-history of how we arrived at that directory hierarchy.
+A <<def_commit_object,"commit" object>> ties such directory hierarchies
+together into a <<def_DAG,directed acyclic graph>> of revisions - each
+"commit" is associated with exactly one tree (the directory hierarchy at
+the time of the commit). In addition, a "commit" refers to one or more
+"parent" commit objects that describe the history of how we arrived at
+that directory hierarchy.