GL_RGBA_FLOAT16_ATI with glTexImage2D -> How?

OpenGL OpenGL: Basic Coding
1

fp32 version: glTexImage2D(imgTarget, mipMapLevel, GL_RGBA_FLOAT16_ATI, imageg->getWidth(mipMapLevel), imageg->getHeight(mipMapLevel), 0, 4, GL_FLOAT, src);

I got it working for fp32 textures, but I simply can’t find the GL_FLOAT equivalent for fp16, like GL_FLOAT!& or something… The doc’s say:

  1. Should we expose a GL_FLOAT16_ATI pixel type so that the 16 bit
    float textures can be directly loaded?
    RESOLUTION: This will be exposed in a separate extension.

But where?

Regards,
Thomas