Sheet reference support in the T3DataStructure

If Data Structures are arranged in a collection of sheets you can choose to store one or more sheets externally in separate files. This is done by setting the value of the <[sheet ident]> tag to a relative file reference instead of being a definition of the <ROOT> element.

Main Data Structure:

EXT:my_extension/Configuration/FlexForms/MyFlexForm.xml 
<T3DataStructure>
    <sheets>
        <sDEF>EXT:my_extension/Configuration/FlexForms/sheets/DefaultSheet.xml</sDEF>
        <s_welcome>EXT:my_extension/Configuration/FlexForms/sheets/WelcomeSheet.xml</s_welcome>
    </sheets>
</T3DataStructure>
Copied!
EXT:my_extension/Configuration/FlexForms/sheets/DefaultSheet.xml 
<T3DataStructure>
    <ROOT>
        <sheetTitle>My General Sheet</sheetTitle>
        <type>array</type>
        <el>
            // ...
        </el>
    </ROOT>
</T3DataStructure>
Copied!

and the same for the other sheet WelcomeSheet.xml.