The Word template based export works with template files that are normal Word files but which contain text fragments that constitute template language elements.
The template language elements in the Word content are introduced using the [[ marker and are closed using the ]] marker.
Template language elements can either be statements or expressions.
 

While generating the Word document the template language elements are executed and for statements and expressions the execution may have a context-item associated with it.
Context-items can be JIRA entities such as JIRA issues, projects, groups, users or text and numbers.
 

A statement encloses a block of text. All statements are introduced using the marker [[\name]] and closed using the marker [[/name]] where "name" is the name of the statement. 
All text between these two markers is considered part of the statement and is used during the generation of the Word contents.
A statement can contain further statements or expressions. 
 

Expressions can be either simple, path or composite expressions.

• Simple
  The expression only refers to textual content such as a number or display text.
• Path
  The expression is provided in a path notation in which each path element is separated by a dot. 
  Using a path expression allows you to refer to values of subsequent context-items.
• Composite
  The expression is formed by a single expression or the combination of two expressions using operators such as =, <>, <, >, +, etc. resulting in a context-item representing the combination result.

An expression is a stand-alone text fragment of the form [[$name]] where "name" is the name of the expression. 
The expression text fragment will be substituted during the generation with the evaluation value of the expression.