PR#5415: clarify how to obtain closures for callbacks. Plus: document the compare_ext field of custom operations.
PR#5415: clarify how to obtain closures for callbacks.
Plus: document the compare_ext field of custom operations.


git-svn-id: e40234e4c881bffaae8eee4067ddafaf89232d37@12281 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

eliberis/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,eliberis/ocaml,eliberis/ocaml,msprotz/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,yunxing/ocaml,msprotz/ocaml,msprotz/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,yunxing/ocaml,msprotz/ocaml,eliberis/ocaml