# default

The default type is an implementation dependent special type which stores the default reference.

- Default context is a set of branches (cf. altstep) that is implicitly appended at the end of all alt statements (except if the alt has an else branch) and after all stand-alone receive/timeout/done â¦ statements. When no branch of the alt matches the received message, the previously activated default(s) are examined.
- A default reference is the result of an activate operation.
- The reference can be used to deactivate a given default.
- The special value null is available to indicate an undefined default reference, e.g. for the initialization of variables to handle default references.
- It is possible to have several defaults activated at same time and deactivate them one by one. The last activated default will be placed first in the list of the activated defaults.

Related keywords:

- activate
- alt
- alstep
- deactivate
- null

### default

Example 1:

var default vd_MyDefaultVar := null;

A variable called vd_MyDefaultVar is declared and initialized with the null value.

BNF definition of default