At U11 and below, non-contact training only.
At U12 and 13, in addition to the above, non-contact matches and competition (if approved in writing by the GRFU).
At 14, 15 and 16, in addition to the above, XRugby7s contact matches and competition and preparation (if approved in writing by the CB).
At U17 and 18, in addition to the above, 7 a-side contact matches and competition and preparation (if approved in writing by the CB).
Further details and Regulation 15 can be found here,
RFU Regulation 15