IBM 5155 Manual To Operations page 332

IBM's Limited Warranty applies to the Prototype Card
option only as it was manufactured; it ceases to apply
once the card is altered or modified. Examine this card
carefully before making modifications.
Note: As sold by the manufacturer, this Prototype
Card does not require certification under the FCC's
rules for Class B devices. The user is responsible for
any interference to radio or TV reception that may
be caused by a user-modified Prototype Card.
2 Prototype Card
January 1984