TEXTURE_EXTERNAL_OES target with RGB color format as the render target

In `EXT_YUV_target`, it says:

> To perform the YUV rendering capability in this extension an application
> will attach a texture to the framebuffer object as the color attachment.
> If the texture has a target type of TEXTURE_EXTERNAL_OES with YUV color
> format then the GL driver can use this framebuffer object as the render
> target, TEXTURE_EXTERNAL_OES target with RGB color format are not allowed
> with this extension.

So which extension allow TEXTURE_EXTERNAL_OES target with RGB(and RGBA) color format as the render target? I searched the project, can not find infomation.

I'm now work in Mali G52 with `EXT_YUV_target` and `EGL_EXT_image_dma_buf_import.txt`, which allow external texture like RA24, and allow bind to framebuffer, write by glClear or shader. But I can not find which extension allow this. Only `EXT_YUV_target` allow bind TEXTURE_EXTERNAL_OES to framebuffer, but do not allow RGB.

Is it better to provide another extension to ensure this operation?

Start by reading the quoted TEXTURE_EXTERNAL_OES restriction in EXT_YUV_target and compare it with EGL_EXT_image_dma_buf_import.txt, especially the RA24 use case described here. Done would be a documented identification of an extension permitting RGB or RGBA external textures as render targets, or a clearly scoped proposal for a new extension.

Written by the indexing model from the issue text.