When a VARCHAR column has this default value, the column is the filename column in an external blob definition.
When a column has this type of default, the column_default_value column in the TableSchema.SYS_COLUMN system table contains
the prefix and extension strings found in the external blob definition, in the form 'prefix|extension'.
The default value of existing tables can be determined by querying the column_default column in the TableSchema.SYS_COLUMNS
system table.
Syntax