Yes, there was whitespace. I tried without whitespace without success.
``` $var(delimiter) = ","; $var(count) = $(hdr(History-Info)[*]{param.count,$var(delimiter)});
ERROR: pv [pv_trans.c:2631]: tr_parse_paramlist(): invalid separator in transformation: count,$var(delimiter)} ERROR: <core> [pvapi.c:1629]: tr_lookup(): error parsing [{param.count,$var(delimiter)}] ERROR: <core> [pvapi.c:1010]: pv_parse_spec2(): bad tr in pvar name "hdr" ERROR: <core> [pvapi.c:1036]: pv_parse_spec2(): invalid parsing in [$(hdr(History-Info)[*]{param.count,$var(delimiter)})] at (4) ```