Change from patient coordinate system to device

src/schema/objects/metadata.yaml

@@ -3372,8 +3372,11 @@ TablePosition:
   description: |
     The table position, relative to an implementation-specific reference point,
     often the isocenter. Values must be an array of three distances in
-    millimeters, respectively right, anterior and superior (RAS+) where the
-    origin is defined by the image affine.
+    millimeters. The coordinates are respectively right, anterior and superior
+    (RAS+) as if it were acquired in head first supine (HFS) orientation. In
+    other words, moving the table into the scanner will increase the 3rd value
+    in the array (even in the feet first orientation). The origin is defined by
+    the image affine.
   type: array
   minItems: 3
   maxItems: 3