Texas Instruments TI-83 PLUS - Manual (Page 515)

TI-83 Plus Programming 512
These menu items direct the flow of an executing program. They make it
easy to repeat or skip a group of commands during program execution.
When you select an item from the menu, the name is pasted to the
cursor location on a command line in the program.
To return to the program editor without selecting an item, press ‘ .
Controlling Program Flow
Program control instructions tell the TI-83 Plus which command to
execute next in a program. If , While , and Repeat check a defined
condition to determine which command to execute next. Conditions
frequently use relational or Boolean tests (Chapter 2), as in:
If A<7:A+1 ! A
or
If N=1 and M=1:Goto Z
If
Use If for testing and branching. If condition is false (zero), then the
command immediately following If is skipped. If condition is true (nonzero),
then the next command is executed. If instructions can be nested.