→Retentive and non-retentive variable: RETAIN, NON_RETAIN

Retentive variables are variables that are stored in a way that their values are conserved without changes for a →warm restart after the application has been stopped. Non-retentive variables are initialized anew with their →initial value, in case of a warm restart.

Declaration of	in ST-editor, by using a keyword	in a graphical editor, by using a prefix (e.g. within the FBD-editor when creating a value field with a new variable)
retentive →variables	`RETAIN`	`R`
non-retentive variables	`NON_RETAIN`	`NR`

The keywords are only allowed for the sections VAR , VAR_INPUT , VAR_OUTPUT and VAR_GLOBAL but also for declared →function block instances. They are not allowed for program instances within the PLC-object .
The prefix is only allowed for internal variables, →input variables , →output variables and →global variables .