Itanium(TM) architecture instructions are organized in instruction groups. Each instruction group contains one or more statically contiguous instruction(s) that can execute in parallel. An instruction group must contain at least one instruction; there is no upper limit on the number of instructions in an instruction group.
An instruction group is terminated statically by a stop, and dynamically by taken branches. Stops are represented by a double semi-colon (;;). The programmer can explicitly define stops. Stops immediately follow an instruction, or appear on a separate line. They can be inserted between two instructions on the same line.
Refer to the Intel® Itanium(TM) Architecture Software Developer’s Manual for more detailed information about instruction groups.