The result data type of a window aggregate UDF is based on the return type of the aggregate UDF, which is specified in the RETURNS clause of the CREATE FUNCTION statement.
The default format of a window aggregate UDF is the default format for the return type. For information on the default format of data types and an explanation of the formatting characters in the format, see “Data Type Formats and Format Phrases” in Teradata Vantage™ - Data Types and Literals, B035-1143.