I suspect that this document is uncommon. Army Form W.3194 appears to be proof of attestation under the Group Scheme or Derby Scheme. This man fell into Group 37 which indciates that he was a married man, born in 1884, when he attested on the 15th December 1915. Apart from this useful information, we also see the man's home address and that he attested at Melton Mowbray. Apart from a postage stamp, the reverse of this form is blank.