# 23 Emulator Properties: `Property`

The `Property` module provides operations to query and possibly update Mozart system-related parameters that control various aspects of the Mozart engine and system modules.

The most important properties can be controlled graphically by means of the Mozart Panel, which is described in ``Oz Panel''.

The properties are accessible to the programmer by operations resembling the operations on dictionaries: `Property.put` sets a property, whereas `Property.get` and `Property.condGet` access properties. The operations are described here in more detail.

## 23.3 The Programming Interface

`get`

  > `{Property.get` `+LI``` `X``}`

  Returns the property stored under the key `LI` (a literal or an integer). Raises an exception, if no property with key `LI` exists.

`condGet`

  > `{Property.condGet` `+LI``` `X``` `Y``}`

  Returns the property stored under the key `LI` (a literal or an integer). If no property with key `LI` exists, `X` is returned.

`put`

  > `{Property.put` `+LI``` `X``}`

  Stores the property `X` under key `LI` (a literal or an integer). Raises an exception, if the property is read-only.