PlaidCloud expressions and filters provide use of most non-administrative PostGIS methods. PostGIS methods are accessed by prefixing the standard method name with
ST_LocateBetween(geometry geom, float8 measure_start, float8 measure_end, float8 offset);
func.ST_LocateBetween(geometry geom, float8 measure_start, float8 measure_end, float8 offset)
PostGIS Official Documentation for this method can be found here.
Additional capabilities and usage examples can be found in the PostGIS documentation.