This read-only object indicates, per the source description, whether timing group 1 associated with this card participates in the card clock, reporting group-clock when it does not and card-clock when it does. Admins use it to understand this card's involvement in group 1 of the TDMTG timing hierarchy, part of the broader clock distribution scheme spanning three groups. A cdx6500TdmtgGroup1ClkParticipation of card-clock(2) indicates this card's group 1 timing is participating in the card clock, distinct from groups 2 and 3 which are reported separately.