SVG.

The W3C specification calls SVG a language for describing two-dimensional graphics and an application of XML, with three kinds of object: vector graphic shapes such as paths, images and text. Because it is open and plain text, cutting software and many platforms read it as a vector file. That third object type is the catch. An SVG can hold an embedded bitmap and nothing else, and a cutter or a separation RIP then has no paths to follow, whatever the extension says. Text is the other trap: live type in an SVG depends on the receiving machine having the font, so outline it before sending. DTG, DTF and sublimation print pixels, so an SVG sent there is rasterised somewhere before the print head, and the file has lost its advantage. Check the file in a plain viewer before upload: if zooming in shows pixels, it is not the vector the job needs.