imp and environment variables...

Could someone tell me what env variable imp uses to find its messages. Whenever I use imp, specifying input from a tape device I get the error...

Import file: expdat.dmp > /dev/rst1
Message not found ; file=/usr/oracle//imp<language>.msb

I guess there's a null variable between the two adjacent slashes in the second line. What's the variable? And why do I only get it when I specify a tape device? And why doesn't exp give a similar message. And how long is a piece of string? And what's the meaning of life? And...

Michael (going slowly insane).

-- 
Michael Collier (Programmer)                           The Computer Unit,
Email: M.P.Collier_at_city.ac.uk                          The City University,
Tel: 071 477-8000 x3769 (general) or x8199 (MAC)       London,
Fax: 071 477-8565                                      EC1V 0HB,