This is XL/XE monitor output connector. Note: this info is incomplete, some
models are lacking certain outputs.
400 and 600XL completely lack monitor port.
XL line lacks separate chroma signal. (Contradicts previous statement for 600XL)
XEGS has only RCA jack (with composite video).
XEP80 has RCA jack (with composite video).
This is XL/XE monitor output for SECAM based Ataris.