Torben,
Thank you but still confused. The link you sent me said:
"Flex and Bison are needed to build a CVS checkout or if you changed the actual scanner and parser definition files. If you need them, be sure to get Flex 2.5.4 or later and Bison 1.875 or later."
My question was about the use of 'smaller than'. I read this as any version from Bison 1.875 onwards (i.e. later or greater than) is acceptable.
Regards
Richard
