NotebookLocate["tag"] locates all cells with the specified tag in your currently selected notebook, selecting the cells and scrolling to the position of the first one.
NotebookLocate["file", "tag"] if necessary opens the notebook stored in file, then locates cells with the specified tag.
NotebookLocate sets the current selection to contain all cells with the specified tag.
If the cells are in closed groups, NotebookLocate will open all these groups.
NotebookLocate is used for following hyperlinks within one notebook or between notebooks.
NotebookLocate searches for tags in the list given as the setting for the CellTags option of each cell.
See The Mathematica Book: Section 2.10.3.
See also: NotebookFind, NotebookOpen, SetSelectedNotebook, ButtonBox.