how to run hashcat legacy rules on new hashcat v3?

[Kgx Pnqvhm]

(This is related to my other question.)

In an attempt to run rules that I previously had to run on CPU hashcat legacy, in hashcat v3, I try:

hashcat64.exe  --opencl-device-types 1

Which gets:

OpenCL Platform #1: NVIDIA Corporation
======================================
- Device #1: GeForce GTX 970, skipped

OpenCL Platform #2: Intel(R) Corporation
========================================
- Device #2: Intel(R) Core(TM) i3 CPU         550  @ 3.20GHz, 4061/16247 MB allocatable, 4MCU

But most of the rules get this warning, like:

WARNING: Cannot convert rule for use on OpenCL device in file  testCPU.rule on line 1741: @a

So how do I run a rule like "@a"?

Edited:
It turns out that either on the CPU alone or the GPU alone, the same 20 of the 2,379 rules do run.
(Edited later: I found that those 20 were simple "append" rules that shouldn't hav been in the CPU-only collection file.)
So both OpenCL devices reject the same rules.
But the question remains how to run a rule file that ran OK on CPU hashcat-legacy on the new hashcat v3?