In metadata an indicator is a Boolean value that may contain only the values true or false. The definition of an Indicator must include the meaning of a true value and should also include the meaning if the value is false.
If a data element may take another value to represent e.g. unknown or not applicable, then a Code should be used instead of an Indicator, and the meanings of all possible values should be clearly defined.
Example of Use of Indicator in XML
Standards that use the indicator representation term
The following metadata registry standards use the term indicator