Mark ring is pushed at start of every successful search and when
jump to line occurs. The mark is set on jump to buffer start or end.
\\[point-to-register] save current position in character register.
-' go to position saved in character register.
+\\=' go to position saved in character register.
s do forward incremental search.
r do reverse incremental search.
\\[View-search-regexp-forward] searches forward for regular expression, starting after current page.