This attribute defines the framing of the DS1 tributary.
d4 defines a framing pattern of 12 frames per multiframe.
esf defines a framing pattern of 24 frames per multiframe.
d4Cas defines a framing pattern of 12 frames per multiframe with
channel associated signalling.
esfCas defines a framing pattern of 24 frames per multiframe with
channel associated signalling.
For the 4pDS3ChAtm card, only d4 and esf framing patterns are
permitted.