The size limit for a BLOB is 1 gigabyte.
You cannot use BLOB values in an index.
You cannot have an array of BLOB fields.
You cannot pass a BLOB as a parameter (but you can pass a temp-table that contains a BLOB field as a parameter).
BLOB fields are only allowed in temp-tables that are NO-UNDO.
You cannot define a local program variable as a BLOB.
You cannot use ASSIGN triggers for a BLOB field.
The initial value for a BLOB must be the Unknown value (?).
You must copy a BLOB to a MEMPTR to read or edit it.
The RAW-TRANSFER statement skips BLOB fields, assigning the Unknown value (?) to the BLOB field in the target record.