To use the DCTL as an IDT:
Input Transform: Bypass/No Input Transform
in v16, Right click on clip(s), DaVinci CTL > Your required dctl
In v17, Right click in clip(s), LUTs > Your required dctl
In v17, you can also load a DCTL for use directly as an IDT (can be loaded via Input Transform), However, the code is very different and the specs appear to be more for Display referred transforms:
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