You can retrieve both the Data Type and the Modeling Type of a column
Names Default To Here( 1 );
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
show(dt:Height << Get Data Type());
show(dt:Height << Get Modeling Type());
The documentation for these 2 elements is in the Scripting Index
Help==>Scripting Index==>Data Table==>Column Scripting
Jim