Hi,
It took me a moment to realize that the vertices column in the POP to DAT primitive output actually refers to point indices, not vertex indices. The only place I found this mentioned was in the Operator Snippets (/ui/dialogs/OPSnippetsShell/OPSnippetsOnDemand/POP/_conceptsPOP/example1/popto_primitives1).
It makes sense once you carefully review the prim:vindex and pindex outputs when extracting vertices, but it would be great to have more detailed and specific help on the Extract parameter and the POP to DAT docs.
Ben