1. A computer program product for transforming instruction specifiers of a computing environment, the computer program product comprising: a non-transitory computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: obtaining, by a processor, from a first instruction defined for a first computer architecture, a non-contiguous specifier, the non-contiguous specifier having a first portion and a second portion, wherein the obtaining comprises obtaining the first portion from a first field of the instruction and the second portion from a second field of the instruction, the first field separate from the second field; generating a contiguous specifier using the first portion and the second portion, the generating using one or more rules based on the opcode of the first instruction; and using the contiguous specifier to indicate a resource to be used in execution of a second instruction, the second instruction defined for a second computer architecture different from the first computer architecture and emulating a function of the first instruction.