7 lines (6 with data), 252 Bytes

m255a 0 128 0 12:00:00 04/01/1990
# Start time=12:00
# First beat=12:08:23.328
# <age-range>: 35-39, <sex>: Male, <medication>: None
# <RR-low-limit(sec)>: 0.468,  <RR-high-limit(sec)>: 1.453
# Note: recording with a timing signal, flutter-compensated