Bookmarks allow you to mark and navigate back to a line of code within an AutoLISP program that is open for edit in a text editor window.
The Visual LISP text editor allows you to place up to 32 bookmarks in each open text editor window. Once 32 bookmarks are set, adding a new bookmark results in the oldest bookmark being removed.
Each text editor window maintains its own set of bookmarks, and the bookmark navigation tools let you walk through the marks within each window independently of the other windows. A set of bookmarks within a window is known as a bookmark ring. You can step either forward or backward through the ring, and eventually return to the starting point.
Whenever you step to a bookmark, Visual LISP automatically places a marker at the location you are stepping from. In effect, the marker for the place you are jumping to is moved to the place you jumped from. This makes it easy to return to your original location just by stepping back in the opposite direction, or by cycling through all the bookmarks until you get back to the starting point.