From Svg wiki

SVG Tiny 1.1 Plus (SVGT 1.1+) is a creation of the mobile commercial ecosystem requiring additional features not found in SVG Tiny 1.1. SVG Tiny 1.1 was completely finalized in January 2003, and the lead-in time for the first SVG Phones to reach the market took about a year. In that time, mobile phones capabilities for rendering graphics had already evolved and certain features that had been stripped in SVGT 1.1 were now realistic expectations. Under the pressure of various mobile operators and service providers, the whole mobile SVG ecosystem (manufacturers, operators and SVG vendors) worked together to create SVGT 1.1+.

Relationship to SVGT 1.1 and SVGT 1.2

SVG Tiny 1.1 Plus is not a completely rogue effort and has solid technical foundations. For instance, SVGT 1.1+, on a features point of view, sits directly in between SVGT 1.1 and SVGT 1.2. In other words, SVG Tiny 1.1 is a strict subset of SVG Tiny 1.1+, which itself is a strict subset of SVG Tiny 1.2. This means that any content authored in SVGT 1.1+ will be displayed the exact same way in an SVGT 1.2 User Agent.

Additional Features

There are two main features found in SVGT 1.1+ that are not found in SVGT 1.1: opacity and gradients. These two features are supported exactly the same way as they will be in SVGT 1.2. In the case of opacity, only the fill-opacity and stroke-opacity attributes are supported, the opacity attribute being too costly by requiring an off-screen buffer for alpha composition. As for gradients, both the <linearGradient> and <radialGradient> elements are supported with restrictions being that the gradientTransform, spreadMethod and xlink:href attributes are not available. Additionally, it is worth noting that the stop-opacity attribute is allowed on the <stop> element.

Support in Authoring Tools

SVGTiny 1.1+ is well supported in mobile SVG authoring tools, such as Adobe Illustrator, Beatware Mobile Designer and Ikivo Animator.