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The INCLUDE directive automatically quotes the filename specified, as per INSERT described above. When a variable contains the name of the template for the INCLUDE directive, it should be explicitly prefixed by '$' or double-quoted

    [% myheader = 'my/misc/header' %]
    [% INCLUDE   myheader  %]            # 'myheader'
    [% INCLUDE  $myheader  %]		 # 'my/misc/header'
    [% INCLUDE "$myheader" %]		 # 'my/misc/header'