Laws of Cricket 1947 Code - Law 11
The Pitch shall not be completely covered during a match unless special regulations so provide; covers used to protect the bowlers' run up shall not extend to a greater distance than 3 1/2 feet in front of the Popping creases.
Note on Law 11
1. It is usual under this Law to protect the bowlers' run up, before and during a match, both at night and, when necessary, during the day. The covers should be removed early each morning, if fine.
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