19 {number of normally included comment lines}

Here's a brief free-form tutorial on how to decipher the MTP data: Data groups consist of the following group of lines per 15-second observing cycle.

First line is: UTSEC, number of retrieval levels in following table, Pressure Altitude, Pitch, Roll, Outside air temp (K), tropopause altitude #1 (km), tropopause altitude #2 (km) [if present], potential temperatures of tropopause #1 and #2, latitude, longitude, & lapse rate near flight level. The 1-liners (for each cycle) can be stripped & imported into a spreadsheet for convenient plotting of trop altitude, lapse rate, etc. The tropopause altitudes are calculated by cubic spline interpolation of the retrieved altitudes using the WMO definition (that is, trop #1 is lowest altitude where average lapse rate > -2 K/km from initial -2 K/km point to any point within 2 km; trop #2 occurs above first trop after lapse rate is < -3K/km for >1 km, and then first trop definition applies, possibly from within the 1 km region.)

Remaining set of lines for each cycle consist of 5 columns: col#1 is pressure altitude (meters), col#2 is temperature from MTP (Kelvin), col#3 is temperature error estimate (K), col#4 is geometric altitude (meters), based on GPS altitude (meters), and col#5 is molecular air density [1E+21/m3].