# C.27.2.1 Points Macro Attribute Descriptions

All Attributes within this module containing points or vectors are in x-y-z order. If multiple elements are encoded, the ordering is x
_{
1
}
,y
_{
1
}
,z
_{
1
}
,…,x
_{
n
}
,y
_{
n
}
,z
_{
n
}
.

The points are in the coordinate system identified by the Frame of Reference UID (0020,0052). To map these points into the coordinate system of another SOP Instance a Spatial Registration Instance can be used.

## C.27.2.1.1 Point Coordinates Data

When referencing individual points the index of the first point shall be 1.