The precision of the render texture's depth buffer in bits (0, 16, 24/32 are supported).
When 0 is used, then no Z buffer is created by a render texture.
16 means at least 16 bit Z buffer and no stencil buffer. 24 or 32 means at least 24 bit Z buffer, and a stencil buffer.
When requesting 24 bit Z Unity will prefer 32 bit floating point Z buffer if available on the platform.
See Also: format, width, height.