M4PATCH allows specification of the patching at MarkIV stations. There are limited options so far - ASTRO and GEO1.
ASTRO is the default and has the odd numbered VCs on IF 1 (IFCHAN 1N and 1A) and even numbered VCs on IF 2 (IFCHAN 2N and 2A). Note that 1N and 2A are often connected to the same thing. Same for 2N and 1A. IF 3 is not used.
GEO1 is for a geodetic style patching. The pattern is:
VCs 1-2 IF1 low = 8180-8300 MHz " 3-4 IF1 high = 8300-8580 MHz " 5-8 IF3 = 8680-8980 or 8280-8580 MHz " 9-10 IF2 low = 2120-2240 MHz " 11-14 IF2 high = 2240-2520 MHz