Need help identifying this 4th lube line on my Haas DM-1

I'm in the process of purging my lube lines to unclog the lines.

On my manifold inside the cabinet I have (4) Lines

One is the X-Axis
One is the Y
One is the Z

But I'm not sure what this extra line is ( the one with the yellow arrow )

I'm guessing the spindle? ( but isn't that being lubed from the oil tank at the bottom of the cabinet? )

Thanks,

Kent

Attachment 504588

Just a quick update.....

I followed the line and it goes to the side tool carousel gear