1. A method for executing instructions of a transaction in a transaction execution (TX) computing environment with transactional memory, the method comprising: executing, by a processor, a latent modification instruction (LMI) within the transaction, the transaction comprising a set of target instructions following the LMI in program order in an instruction stream, each of the target instructions having an associated function, the LMI at least partially specifying a substitute function to be substituted for the associated function; and executing, by the processor, a next sequential instruction (NSI) and at least one of the target instructions within the transaction, the NSI following the LMI in program order in the instruction stream, wherein the executing the at least one of the target instructions employs the substitute function at least partially specified by the LMI, wherein the set of target instructions includes a second part of a combination instruction, wherein the LMI is a first part of the combination instruction, wherein the function of the second part of the combination instruction is a null function, and wherein the first part of the combination instruction and the second part of the combination instruction combine to specify the substitute function.