1 env.X: Prefixing a variable with "env." will return the shell's environment variable. For

example, ${env.PATH} contains the PATH environment variable. Note: While environment

variables themselves are case-insensitive on Windows, lookup of properties is case-sensitive. In

other words, while the Windows shell returns the same value for %PATH% and %Path%, Maven

distinguishes between ${env.PATH} and ${env.Path}. As of Maven 2.1.0, the names of

environment variables are normalized to all upper-case for the sake of reliability.

2 project.x: A dot (.) notated path in the POM will contain the corresponding element's

value. For example: 1.0 is accessible via

${project.version}.

3 settings.x: A dot (.) notated path in the settings.xml will contain the corresponding

element's value. For example: false is

accessible via ${settings.offline}.

4 Java System Properties: All properties accessible via java.lang.System.getProperties()

are available as POM properties, such as ${java.home}.

5 x: Set within a element. The value may be used as ${someVar}.