What is MPEG4 Simple Profile Level 0?

在MPEG-4 14496-2中，没有simple profile level 0的定义，最小的是simple profile level 1，那么simple profile level 0是什么？如下：

I have heard of a Level 0 for Simple Profile, what is it?

Level 0 of the simple profile was designed to target to the wireless industry where screen sizes are small, and processing power is low. Level 0 has the same functionality as the other Simple profile levels but with the following additional restrictions.

1. The maximum frame rate shall be 15 frames per second;
2. The maximum f_code shall be 1;
3. The intra_dc_vlc_threshold shall be 0;
4. The maximum horizontal luminance pixel resolution shall be 176 pels/line;
5. The maximum vertical luminance pixel resolution shall be 144 pels/VOP;
6. If AC prediction is used, the following restriction applies : QP value shall not be changed within a VOP (or within a video packet if video packets are used in a VOP). If AC prediction is not used, there are no restrictions to changing QP value.

Level 0 is available in the Streaming Video Profile Amendment.