[help-texinfo] line offset strangeness in info index

[Robert Dodier]

Hello,

I'm attempting to generate a byte-offset index for a document
generated by makeinfo. In the makeinfo index there are items of the form

* quad_qaws:                             Definitions for QUADPACK.
                                                            (line  485)

I have found that the first line of a @deffn or @defvr item can
(usually) be located by jumping (n - 1) lines from the unit separator
character (ctrl-underbar) at the top of the node. However it
appears that (unit separator) + (n - 1) lines is one line too much
when the jumped-to item is a ' -- Function: ...' item which spans
two lines. E.g. with something like

-- Function: quad_qaws (<f(x)>, <x>, <a>, <b>, <alpha>, <beta>,
         <wfun>, <epsabs>, <limit>)

then jumping (n - 1) lines from the unit separator puts me on the
line '<wfun>, <epsabs>, <limit>)', not the '-- Function: quad_qaws'
preceding it. Jumping (n - 2) lines is just right in this case, but
there doesn't appear to be a way to know whether it should be
(n - 1) or (n - 2) without actually trying it.

I wonder if that behavior is to be expected. Be that as it may,
I guess I'll have to search backwards to find '-- Function:'.

All the best,
Robert Dodier