# What does R,A,S stands for?

**URL:** <https://discourse.slicer.org/t/what-does-r-a-s-stands-for/22104>\
**Category:** Support\
**Created:** [February 22, 2022, 7:54am UTC](https://discourse.slicer.org/t/what-does-r-a-s-stands-for/22104 "2022-02-22T07:54:32Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Kane\_Daizah](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/kane_daizah/32/13600_2.png) [@Kane\_Daizah](https://discourse.slicer.org/u/Kane_Daizah)\
**Post date:** [February 22, 2022, 7:54am UTC](https://discourse.slicer.org/t/what-does-r-a-s-stands-for/22104/1 "2022-02-22T07:54:32Z")

</div>

Hi,  
I’d like to export the Cartesian coordinates of the centerline which is extracted by extract centerline mode. What does R,A,S stands for? Is they correspond to x, y, z in Cartesian coordinate?

 ![WeChat Image_20220222155450](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/3/d/3d895c6233f977b5474ea22857f19f90a0fcc03a.png)

---

<div class="post-metadata">

**Author:** ![ebrahim](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ebrahim/32/13403_2.png) [@ebrahim](https://discourse.slicer.org/u/ebrahim)\
**Post date:** [February 22, 2022, 10:52am UTC](https://discourse.slicer.org/t/what-does-r-a-s-stands-for/22104/2 "2022-02-22T10:52:32Z")

</div>

Right, anterior, superior. These are anatomical coordinates, see [Coordinate systems - Slicer Wiki](https://www.slicer.org/wiki/Coordinate_systems)

---

<div class="post-metadata">

**Author:** ![DIV](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/div/32/12816_2.png) [@DIV](https://discourse.slicer.org/u/DIV)\
**Post date:** [March 1, 2022, 6:12am UTC](https://discourse.slicer.org/t/what-does-r-a-s-stands-for/22104/3 "2022-03-01T06:12:00Z")

</div>

Graham Wideman also has a relevant page on that at his website:  
[http://www.grahamwideman.com/gw/brain/orientation/orientterms.htm](http://www.grahamwideman.com/gw/brain/orientation/orientterms.htm)