a string.  This member allows the formatting expression to be accessed in
    the ValueConv function of user-defined Composite tags, which provided a mechanism for
    arguments to be passed to the ValueConv function.</td></tr>

<tr><td>FORCE_WRITE</td><td>Hash reference for metadata types that are being forced to be
    rewritten (see Extra ForceWrite tag)</td></tr>

<tr><td>FOUND_TAGS</td><td>Found tags with proper case and order</td></tr>

<tr><td>GLOBAL_TIME_OFFSET</td><td>Time offset hash for first shi