From the core gadget specification:
- If the /@specificationVersion attribute or any /ModulePrefs/Require/@version or /ModulePrefs/Optional/@version attributes are absent, they are assumed to have the value "1.0".
- For Gadgets using an OpenSocial specification version 2.0 or greater, Containers MUST render those Gadgets in HTML5 by default. If a Container supports rendering Gadgets with a specification version less than 2.0, those Gadgets SHOULD continue to be rendered in browser quirks mode.
currently, PHP shindig does not set the default specification version to 1.0, and does not use quirks mode for specification versions < 2.0