SWI-Prolog syntax allows “_” to define “digit groups” in integers. This also works with rationals (which are just <integer>r<integer>).
But underscores aren’t allowed in floating point:
?- X = 123_456.23 .
ERROR: Type error: `dict' expected, found `123456' (an integer)
It would be nice to also if “_” were allowed in floating point numbers … can the syntax be adjusted to allow this, or does the “.” for dicts prevent it?