Including files in from the dictionary files

All, I have a question regarding including files. In the radiusd.conf I can include a file: $INCLUDE /path/to/file $INCLUDE ${prefix}/file However, in the dictionary file I cannot use ${prefix}: Errors reading dictionary: dict_init: /opt/freeradius-1.1.5/etc/raddb/dictionary[6]: Couldn't open dictionary "${prefix}/share/freeradius/dictionary.erx": No such file or directory Error: Errors reading dictionary: dict_init: /opt/freeradius-1.1.7/etc/raddb/dictionary[6]: Couldn't open dictionary "${prefix}/share/freeradius/dictionary.erx": No such file or directory I guess this is normal behaviour, but can anyone explain me why this behaviour is present? Cheers, Wesley