# fn:available-environment-variables - XPath XQuery Reference

Returns a list of environment variable names that are suitable for passing to
               fn:environment-variable, as a (possibly empty) sequence of strings.deterministiccontext-dependentfocus-independentThe function returns a sequence of strings, being the names of the environment variables
            in the dynamic context in some implementation-dependent order.The function is deterministic: that is, the
            set of available environment variables does not vary during evaluation.The function returns a list of strings, containing no duplicates.It is intended that the strings in this list should be suitable for passing to
               fn:environment-variable.See also the note on security under the definition of the
               fn:environment-variable function. If access to environment variables has
            been disabled, fn:available-environment-variables always returns the empty
            sequence.