Fixed & sliding Saddle

LCP = Location Control Plan - This is an internal (to the Design Office & Not issued to the Field) document which is an upgraded Plot Plan with more detailed information about the location of all objects on the projects.
The LCP is created after the P&IDs and the Plot Plan but before the Vendor drawings are submitted. So with the P&ID and the Plot Plan the plant layout Designer can determine which end (saddle) the anchor should be located and marks (X) it on the LCP.

So the anchor location is known before (line 14) the Exchanger Outline is received and marked (line 41, 42 & 43).

Just a different way of doing business.

Er,
I am not sure I understand your definition of "Equipment arrangement layout" (EAL)

If your EAL is an issued document showing all equipment, structures, roads, etc but no coordinates or locating dimensions then it would be like what other people call a "Plot Plan"

If your EAL is not and issued document and is for internal communication between all in-house engineering groups before the 3D Design Model, and shows more definition of all equipment, structures, roads, etc along with all locating coordinates then it would be like the ELC (Equipment Location Control Drawing). The ELC would never be issued out of the office.