From a post by P2 earlier in this thread:
The QAR (for SESMA/FDM/FOQA work) will record as many parameters as the installed data frame is designed for, (QAR software) and at sample rates that the frame is similarly designed for. The DFDR is capable of this as well but typically DFDR data frames are smaller and at less frequent sample rates for many parameters. Sample rates of 16 frames per second are possible but are expensive in terms of storage and recording capability. Sample rates from once every fourth second to eight times per second are common in both DFDR and QAR dataframes.
All this is by way of clarifying that "700 parameters" and "2000 parameters" is not a fixed, determined number. Our own 777 QARS are taking in more than 2600 parameters
(Bolding mine)