A stack of interfolded absorbent sheet products comprising a plurality of absorbent sheets and a method of folding and stacking the same. A user’s service request is performed between a user interface and responding external issuer device. A bound key operation can alternatively receive both ciphertext and a bound key or bound key structure bound to one or more processors, recover or reconstruct a private key based on the bound key or bound key structure, and use the private key to generate plaintext corresponding to the ciphertext. At runtime, graphics commands from the VMs are queued and iteratively sent to the GPU based on a comparison between allocated quantum and a threshold quantum. The accelerators have excellent long-term stability and work well with \u201cdifficult\u201d cements, such as some Japanese OPCs.