From aaf5ea943b29e57359caaeadafae0c427a6aec09 Mon Sep 17 00:00:00 2001
From: zepumph <michael.kauzmann@colorado.edu>
Date: Tue, 5 Nov 2019 14:20:56 -0900
Subject: [PATCH] add doc,
 https://github.com/phetsims/gravity-force-lab/issues/185

---
 .../view/describers/GravityForceLabRulerDescriber.js     | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/js/gravity-force-lab/view/describers/GravityForceLabRulerDescriber.js b/js/gravity-force-lab/view/describers/GravityForceLabRulerDescriber.js
index a8d084d6..4de65578 100644
--- a/js/gravity-force-lab/view/describers/GravityForceLabRulerDescriber.js
+++ b/js/gravity-force-lab/view/describers/GravityForceLabRulerDescriber.js
@@ -47,9 +47,14 @@ define( require => {
     RULER_VERTICAL_REGIONS.indexOf( justBelowCentersString ) );
   const SHOW_RULER_REGIONS = ISLCQueryParameters.showRulerRegions;
 
-  /**
-   */
   class GravityForceLabRulerDescriber {
+
+    /**
+     * @param {Property.<number>} rulerPositionProperty
+     * @param {ModelViewTransform2} modelViewTransform
+     * @param {Array.<number>} viewYPositions - a list of Y positions, least (top) to greatest (bottom)
+     * @param {PositionDescriber} positionDescriber
+     */
     constructor( rulerPositionProperty, modelViewTransform, viewYPositions, positionDescriber ) {
 
       assert && assert( RULER_VERTICAL_REGIONS.length === viewYPositions.length, 'Unexpected number of y positions' );