For record groups, data length semantics can be specified in the Forms Builder and
in the record group column mapping dialog when the datatype is CHAR.
A value of BYTE, CHAR, or Null can be specified.
When Null is specified, the value in the generated fmx file becomes CHAR
if the environment variable NLS_LENGTH_SEMANTICS is set to CHAR
when the fmx file is generated; otherwise, it becomes BYTE.
When a record group is based on a query, the Record Group wizard will set
the data length semantics in the record group column mapping for a CHAR
column based on the semantics of the selected database column.
When a record group is created dynamically (at run time), you can specify
a column's data length semantics as a fifth parameter to the ADD_GROUP_COLUMN Built-in. It can take values of 'BYTE' or 'CHAR' (which are valid
only when the datatype is CHAR), or null, which is the default. A null value in a CHAR
column mapping indicates that the data length semantics is to be taken
from the environment variable NLS_LENGTH_SEMANTICS.
Note that at build time, CHAR indicates CHAR semantics; any other value indicates BYTE semantics). If the record group was created with Form_Scope (the default), then the relevant value is the value of NLS_LENGTH_SEMANTICS that was in effect when the form was compiled. If the record group was created with Global_Scope, then the relevant value is the value of NLS_LENGTH_SEMANTICS that is currently in effect at run time.
About record groups and Lists of values (LOVs)
Creating a query record group at design time