# J.2 Property File Format *Property Files* define properties. Properties are stored in key/value pairs and may only contain plain text. The suffix of these files should be `.properties`, the default Property File for a Build File is `build.properties` ``` # Property files contain key/value pairs key=value # Property keys may contain alphanumeric chars and colons, but # not special chars. This way you can create pseudo-namespaces myapp.window.hsize=300 myapp.window.vsize=200 myapp.window.xpos=10 myapp.window.ypos=100 # You can refer to values of other properties by enclosing their # keys in "${}". text.width=${myapp.window.hsize} # Everything behind the equal sign is the value, you do # not have to enclose strings: text=This is some text, Your OS is ${php.os} ``` Property files may also be formatted in YAML format: ``` # Property files contain key/value pairs key: value # Nested values will be available as concatenated strings after import. E.g., # you may access these values with keys in the form of "myapp.window.hsize". myapp: window: hsize: 300 vsize: 200 xpos: 10 ypos: 100 # You can refer to values of other properties by enclosing their # keys in "${}". text: width: "${myapp.window.hsize}" ```