A radiation attenuation elastomeric material which includes an elastomer in which a powder of metal oxides is dispersed, wherein the powder of metal oxides includes from 70 to 90% by mass of bismuth trioxide, from 5 to 15% by mass of tungsten trioxide, and from 5 to 15% of lanthanum trioxide. A query is executed to determine whether the data indicates the machine has become unavailable. The sheets are releasably securable to the spine and to optionally to a chart cover by means of support pegs. Via the API, the calling application may further indicate an amount of time to wait for an acknowledgment of the asynchronous replicating of the changes before continuing.