The contents of the std script dump extracted from TH20.dat using thstd dump are empty.

[liu10mc]

Command line output

PS G:\thtk\20> thstd -d 20 st01.std
PS G:\thtk\20>

[Phroneris]

Git Bash (by Git for Windows v2.49.0) output:

$ ./thstd -d 20 st01.std
Segmentation fault

[liu10mc]

Found the problem: the std_entry_header in the th20 std file has an additional 20 bytes of data.