Conversion of xlt files to nmbtemplate file format

iWorks Numbers does not natively support the templates from Microsoft Excel (.xlt), which makes xlt to nmbtemplate conversion not that easy. But you could save XLT template as XLS spreadsheet in Microsoft Excel and then import that to Numbers where you can make the .nmbtemplate. But overall converting templates is not that common and some special features can be lost.

Open XLT file    Open NMBTEMPLATE file