7 lines (6 with data), 253 Bytes

m048a 0 128 0 16:00:00 01/07/1990
# Start time=16:00
# First beat=16:11:46.750
# <age-range>: 50-54, <sex>: Female, <medication>: None
# <RR-low-limit(sec)>: 0.671,  <RR-high-limit(sec)>: 1.21
# Note: recording with a timing signal, flutter-compensated