This documentation is not using the current rendering
mechanism and is probably outdated.
The extension maintainer should switch to the new system.
Details on how to use the rendering mechanism can be
found here.
Attributes "Src", "Width" and "Height".
"Option: Insert Data" enables "stdWrap.insertData" for every flexform field (See the example in "Src").
Calculate in "Width" and "Height" (with "stdWrap.prioriCalc = intval").
Use values of prior fields (See the example in "Height").