how do i specify include path?

[Garry Hodgson]

i know i use the -pa flag on the erl command line to specify module
path,
but i can't seem to find the corresponding flag to set include path, so 
it can find the necessary .hrl files when compiling.
i see a -I on erlc, but it doesn't appear to work within erl, when using

 c(modulename).

any clues?
thanks

-- 
Garry Hodgson                   Let my inspiration flow
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