User`s guide

Remarks
You can erase readings from memory at any time, even during a series of
measurements
You can store up to 50,000 readings in memory for the 34410A
(1,000,000 readings for the 34411A/L4411A). If memory overflows, the
new readings will overwrite the first (oldest) readings stored; the most
recent readings are always preserved. In addition, bit 14 is set in the
Questionable Data Register's condition register (see Status System
Introduction).
If fewer than the specified number of readings are currently in memory, an
error will be generated. You can use the DATA:POINts? command to
determine the total number of readings currently in memory.
The instrument clears all readings from memory after a Factory Reset
(*RST command), after an Instrument Preset (SYSTem:PRESet command),
or when mainframe power is cycled.