How do I...

There are several ways to do this - and if you know python its easy to use the RUNPYTHON module, but another approach uses PSEUDOMATH.

The PSEUDOMATH module is a replacement for STORE1/STORE2/MERGE. It can be used to create or manipulate pseudotraces. A pseudotrace has the same dimensions as a trace (number of samples etc.) but is stored as a trace header (and written into the .dth file).

In this example :
- SYNWAVE creates some synthetic traces
- SMUTE loads a tail mute (also called an inner trace mute or off mute) into the SPARE1 header
=> the mute was picked in SV
=> note the mute is NOT applied here
- the first call to PSEUDOMATH creates a copy of the traces, called COPY
- the traces are then all zero'd with TREDIT
- the second call to PSEUDOMATH then copies the (dead) traces into a new pseudotrace called BLANK
- SETHEADER resets the trace type to 0, as TREDIT will have modified this
- the third call to PSEUDOMATH merges the COPY and BLANK pseudotraces, with the SPARE1 header providing the merge point.

This approach could also be used to apply a different sequence to the upper and lower part of a dataset.