For example, frames specify {TAIL ~ operations} to be performed on internal entities such as variables or {HEAD ~ timers}, for example 
For example , frames specify { TAIL ~ operations } to be performed on internal entities such as variables or { HEAD ~ timers } , for example
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH