SQL/MX 2.x Reference Manual (H06.04+)

Limits
HP NonStop SQL/MX Reference Manual—540440-003
C-2
Referential constraints A table can have an unlimited number of referential
constraints, and you can specify the same foreign key in
more than one referential constraint, but you must
define each referential constraint separately.
Schema names 128 characters in length.
Tables ANSI names are three-part name of the form
catalog.schema.object, where each part can be up
to 128 characters long.
The maximum length of a row is 4040 bytes, but not all
of that is available. Depending on data types you use,
NonStop SQL/MX might use some bytes for internal
use.
The clustering key for a table cannot be longer than 255
bytes. If the table has triggers, the clustering key length
cannot be longer than 247 bytes. If the key length is
greater than 247, trigger creation will fail.