# EPOC OPL Guide & Reference Glossary

## Index P

Term | Topic | Meaning | See Also
passed by reference | Using OPXs | A trick used to allow modification of data passed as parameters to a procedure. Normally a copy of all the data is made when you pass a value to a function; if the procedure modifies the copy it gets, the original doesn’t change. The `BYREF` keyword can be used to make a variable parameter into a reference. If a reference is copied, both copies refer to the same object, so if the variable is modified inside the function body the original is modified. |
poll | Advanced Topics | To loop repeatedly waiting for an event. |
procedure | Introducing OPL | A list of statements with a name that can be invoked as a unit. The statements in a procedure are usually executed one by one until the procedure ends, although this order can be altered with certain statements. | statement, execute
procedure prototype | OPL Basics | A procedure declaration with no body. |
process | Advanced Topics | The execution of a program. Many processes can exist on an EPOC device at one time without interfering with one another. |
program | Introducing OPL | Any list of instructions for a computer to follow. For OPL, program means both the program text which is editable in the Program application, and the translated version which can be run by the machine. Each OPL program file contains a single module, and an entire program can be built from many modules. | translate, module, run
public name | Advanced Topics | The caption of an application; this is displayed in the list of open files and programs in the EPOC shell. |