What Characters are Allowed in a Field Name?

In most cases, field (column) names may contain any character except double quote ", period ., or colon :. Underscores are displayed as spaces in the UI.

make_col "ΔT":float64(field3)
make_col "占用率":float64(field4)
make_col "0_3µm":float64(um03)

To reference a field with non-alphanumeric characters in an OPAL statement, use double quotes and prepend @..

make_col temp_difference:@."ΔT"

Regex extracted columns (whether features like Extract From Text or OPAL verbs like extract_regex) are limited to alphanumeric characters (A-Z, a-z, 0-9).