diff --git a/src/Informedica.GenOrder.Lib/OrderVariable.fs b/src/Informedica.GenOrder.Lib/OrderVariable.fs
index dc99323..49b1b85 100644
--- a/src/Informedica.GenOrder.Lib/OrderVariable.fs
+++ b/src/Informedica.GenOrder.Lib/OrderVariable.fs
@@ -129,7 +129,7 @@ module OrderVariable =
                     else
                         vr
                         |> ValueRange.setOptVs ovar.Constraints.Values
-                |> Variable.setValueRange true ovar.Variable
+                |> Variable.setValueRange ovar.Variable
         }
 
 
diff --git a/src/Informedica.GenSolver.Lib/Api.fs b/src/Informedica.GenSolver.Lib/Api.fs
index acb88b2..4f2ff93 100644
--- a/src/Informedica.GenSolver.Lib/Api.fs
+++ b/src/Informedica.GenSolver.Lib/Api.fs
@@ -16,7 +16,11 @@ module Api =
     module Name = Variable.Name
 
 
-    /// Initialize the solver returning a set of equations
+    /// <summary>
+    /// Create a list of Equations from a list of strings
+    /// </summary>
+    /// <param name="eqs">List of strings</param>
+    /// <returns>List of Equations</returns>
     let init eqs =
         let notEmpty = String.IsNullOrWhiteSpace >> not
         let prodEqs, sumEqs = eqs |> List.partition (String.contains "*")
@@ -34,7 +38,17 @@ module Api =
         (parse prodEqs '*' |> createProdEqs) @ (parse sumEqs '+' |> createSumEqs)
 
 
-    let setVariableValues onlyMinIncrMax n p eqs =
+    /// <summary>
+    /// Apply a variable property to a list of equations
+    /// </summary>
+    /// <param name="n">Name of the variable</param>
+    /// <param name="p">Property of the variable</param>
+    /// <param name="eqs">List of equations</param>
+    /// <returns>The variable option where the property is applied to</returns>
+    /// <remarks>
+    /// The combination of n and p is equal to a constraint
+    /// </remarks>
+    let setVariableValues n p eqs =
         eqs
         |> List.collect (Equation.findName n)
         |> function
@@ -42,23 +56,27 @@ module Api =
         | var::_ ->
             p
             |> Property.toValueRange
-            |> Variable.setValueRange onlyMinIncrMax var
+            |> Variable.setValueRange var
             |> Some
 
 
+    /// Solve an `Equations` list
     let solveAll = Solver.solveAll
 
 
+    /// <summary>
     /// Solve an `Equations` list with
-    ///
-    /// * f: function used to process string message
-    /// * n: the name of the variable to be updated
-    /// * p: the property of the variable to be updated
-    /// * vs: the values to update the property of the variable
-    /// * eqs: the list of equations to solve
+    /// </summary>
+    /// <param name="onlyMinIncrMax">True if only min, incr and max values are to be used</param>
+    /// <param name="sortQue">The algorithm to sort the equations</param>
+    /// <param name="log">The logger to log operations</param>
+    /// <param name="n">Name of the variable to be updated</param>
+    /// <param name="p">Property of the variable to be updated</param>
+    /// <param name="eqs">List of equations to solve</param>
+    /// <returns>A result type of the solved equations</returns>
     let solve onlyMinIncrMax sortQue log n p eqs =
         eqs
-        |> setVariableValues onlyMinIncrMax n p
+        |> setVariableValues n p
         |> function
         | None -> eqs |> Ok
         | Some var ->
@@ -66,16 +84,24 @@ module Api =
             |> Solver.solveVariable onlyMinIncrMax log sortQue var
 
 
-    /// Make a list of `EQD`
-    /// to contain only positive
-    /// values as solutions
+    /// <summary>
+    /// Set all variables in a list of equations to a non zero or negative value
+    /// </summary>
+    /// <param name="eqs">The list of Equations</param>
     let nonZeroNegative eqs =
         eqs
         |> List.map Equation.nonZeroOrNegative
 
 
-    let applyConstraints onlyMinIncrMax log eqs cs =
-        let apply = Constraint.apply onlyMinIncrMax log
+    /// <summary>
+    /// Apply a list of constraints to a list of equations
+    /// </summary>
+    /// <param name="log">The logger to log operations</param>
+    /// <param name="eqs">A list of Equations</param>
+    /// <param name="cs">A list of constraints</param>
+    /// <returns>A list of Equations</returns>
+    let applyConstraints log eqs cs =
+        let apply = Constraint.apply log
 
         cs
         |> List.fold (fun acc c ->
@@ -87,8 +113,16 @@ module Api =
         ) eqs
 
 
+    /// <summary>
+    /// Solve a list of equations using a list of constraints
+    /// </summary>
+    /// <param name="onlyMinIncrMax">True if only min, incr and max values are to be used</param>
+    /// <param name="log">The logger to log operations</param>
+    /// <param name="eqs">A list of Equations</param>
+    /// <param name="cs">A list of constraints</param>
+    /// <returns>A list of Equations</returns>
     let solveConstraints onlyMinIncrMax log cs eqs =
         cs
         |> Constraint.orderConstraints log
-        |> applyConstraints false log eqs
+        |> applyConstraints log eqs
         |> Solver.solveAll onlyMinIncrMax log
diff --git a/src/Informedica.GenSolver.Lib/Constraint.fs b/src/Informedica.GenSolver.Lib/Constraint.fs
index 06f64eb..9fcc1f9 100644
--- a/src/Informedica.GenSolver.Lib/Constraint.fs
+++ b/src/Informedica.GenSolver.Lib/Constraint.fs
@@ -12,12 +12,23 @@ module Constraint =
     module Name = Variable.Name
 
 
+    /// <summary>
+    /// Check whether constraint c1 has the same name as constraint c2.
+    /// </summary>
     let eqsName (c1 : Constraint) (c2 : Constraint) = c1.Name = c2.Name
 
 
+    /// <summary>
+    /// Print the constraint as a string
+    /// </summary>
     let toString { Name = n; Property = p } = $"{n |> Name.toString}: {p}"
 
 
+    /// <summary>
+    /// Give a constraint a score based on the property.
+    /// Low scores should be solved first.
+    /// </summary>
+    /// <param name="c">The constraint</param>
     let scoreConstraint c =
             match c.Property with
             | ValsProp vs ->
@@ -29,6 +40,11 @@ module Constraint =
             | _               -> -2, c
 
 
+    /// <summary>
+    /// Order constraints based on their score.
+    /// </summary>
+    /// <param name="log">The logger to log operations</param>
+    /// <param name="cs">The list of constraints</param>
     let orderConstraints log cs =
         cs
         // calc min and max from valsprop constraints
@@ -63,7 +79,15 @@ module Constraint =
             |> List.map snd
 
 
-    let apply onlyMinIncrMax log (c : Constraint) eqs =
+    /// <summary>
+    /// Apply a constraint to the matching variables
+    /// in the list of equations.
+    /// </summary>
+    /// <param name="log">The logger</param>
+    /// <param name="c">The constraint</param>
+    /// <param name="eqs">The list of Equations</param>
+    /// <returns>The variable the constraint is applied to</returns>
+    let apply log (c : Constraint) eqs =
 
         eqs
         |> List.collect (Equation.findName c.Name)
@@ -76,7 +100,7 @@ module Constraint =
         | vr::_ ->
             c.Property
             |> Property.toValueRange
-            |> Variable.setValueRange onlyMinIncrMax vr
+            |> Variable.setValueRange vr
         |> fun var ->
             c
             |> Events.ConstraintApplied
@@ -85,8 +109,17 @@ module Constraint =
             var
 
 
+    /// <summary>
+    /// Apply a constraint to the matching variables and solve the
+    /// list of equations.
+    /// </summary>
+    /// <param name="onlyMinIncrMax">Whether only min incr max should be calculated</param>
+    /// <param name="log">The logger</param>
+    /// <param name="sortQue">The algorithm to sort the equations</param>
+    /// <param name="c">The constraint</param>
+    /// <param name="eqs">The list of Equations</param>
     let solve onlyMinIncrMax log sortQue (c : Constraint) eqs =
-        let var = apply onlyMinIncrMax log c eqs
+        let var = apply log c eqs
 
         eqs
         |> Solver.solveVariable onlyMinIncrMax log sortQue var
diff --git a/src/Informedica.GenSolver.Lib/Equation.fs b/src/Informedica.GenSolver.Lib/Equation.fs
index b7a3e22..a156b49 100644
--- a/src/Informedica.GenSolver.Lib/Equation.fs
+++ b/src/Informedica.GenSolver.Lib/Equation.fs
@@ -336,8 +336,6 @@ module Equation =
             | y::xs ->
                 y |> op2 <| (xs |> List.reduce op1)
                 |> Some
-        // select the right application operator
-        let (<==) = if onlyMinIncrMax then (@<-) else (^<-)
         // perform the calculations on the vars
         let calcVars op1 op2 vars =
             vars
@@ -365,7 +363,7 @@ module Equation =
 
                                 None
                             | Some var ->
-                                let yNew = y <== var
+                                let yNew = y @<- var
 
                                 if yNew <> y then
                                     // log finishing the calculation
diff --git a/src/Informedica.GenSolver.Lib/Solver.fs b/src/Informedica.GenSolver.Lib/Solver.fs
index 81b37d6..fb17f3c 100644
--- a/src/Informedica.GenSolver.Lib/Solver.fs
+++ b/src/Informedica.GenSolver.Lib/Solver.fs
@@ -78,17 +78,27 @@ module Solver =
         , rst
 
 
-    let sortQue onlyMinMax que =
-        if que |> List.length = 0 then que
+    /// <summary>
+    /// Sort a list of equations by the number of
+    /// total values in the equation.
+    /// </summary>
+    /// <param name="onlyMinMax">Whether only min incr max is calculated</param>
+    /// <param name="eqs">The list of Equations</param>
+    let sortQue onlyMinMax eqs =
+        if eqs |> List.length = 0 then eqs
         else
-            que
+            eqs
             |> List.sortBy (Equation.count onlyMinMax) //Equation.countProduct
 
 
-    /// Create the equation solver using a
-    /// product equation and a sum equation solver
-    /// and function to determine whether an
-    /// equation is solved
+    /// <summary>
+    /// Solve a set of equations.
+    /// </summary>
+    /// <param name="onlyMinIncrMax">Whether to only use min, incr and max</param>
+    /// <param name="log">The log function</param>
+    /// <param name="sortQue">The sort function for the que</param>
+    /// <param name="var">An option variable to solve for</param>
+    /// <param name="eqs">The equations to solve</param>
     let solve onlyMinIncrMax log sortQue var eqs =
 
         let solveE n eqs eq =
@@ -222,7 +232,14 @@ module Solver =
                 Error (eqs, m)
 
 
-    //TODO: need to clean up the number check
+    /// <summary>
+    /// Solve a set of equations for a specific variable.
+    /// </summary>
+    /// <param name="onlyMinIncrMax">Whether to only use min, incr and max</param>
+    /// <param name="log">The log function</param>
+    /// <param name="sortQue">The sort function for the que</param>
+    /// <param name="vr">The variable to solve for</param>
+    /// <param name="eqs">The equations to solve</param>
     let solveVariable onlyMinIncrMax log sortQue vr eqs =
         let n1 = eqs |> List.length
         let solve =
@@ -231,12 +248,18 @@ module Solver =
         match solve eqs with
         | Error (eqs, errs) -> Error (eqs, errs)
         | Ok eqs ->
+            //TODO: need to clean up the number check
             let n2 = eqs |> List.length
             if n2 <> n1 then failwith $"not the same number of eqs, was: {n1}, now {n2}"
             else Ok eqs
 
 
-    //TODO: need to clean up the number check
+    /// <summary>
+    /// Solve a set of equations for all variables.
+    /// </summary>
+    /// <param name="onlyMinIncrMax">Whether to only use min, incr and max</param>
+    /// <param name="log">The log function</param>
+    /// <param name="eqs">The equations to solve</param>
     let solveAll onlyMinIncrMax log eqs =
         let n1 = eqs |> List.length
         let solve =
@@ -245,6 +268,7 @@ module Solver =
         match solve eqs with
         | Error (eqs, errs) -> Error (eqs, errs)
         | Ok eqs ->
+            //TODO: need to clean up the number check
             let n2 = eqs |> List.length
             if n2 <> n1 then failwith $"not the same number of eqs, was: {n1}, now {n2}"
             else Ok eqs
diff --git a/src/Informedica.GenSolver.Lib/Types.fs b/src/Informedica.GenSolver.Lib/Types.fs
index 36aa15a..d617829 100644
--- a/src/Informedica.GenSolver.Lib/Types.fs
+++ b/src/Informedica.GenSolver.Lib/Types.fs
@@ -124,8 +124,8 @@ module rec Types =
 
     /// <summary>
     /// Represents a constraint on a `Variable`.
-    /// I.e. either a set of values, or an increment
-    /// or a minimum of maximum.
+    /// I.e. either a set of values, or an increment,
+    /// minimum or maximum.
     /// </summary>
     type Constraint =
         {
diff --git a/src/Informedica.GenSolver.Lib/Variable.fs b/src/Informedica.GenSolver.Lib/Variable.fs
index 3203524..fd74810 100644
--- a/src/Informedica.GenSolver.Lib/Variable.fs
+++ b/src/Informedica.GenSolver.Lib/Variable.fs
@@ -2989,8 +2989,7 @@ module Variable =
         /// </code>
         /// </example>
         let applyExpr y expr =
-            let appl _ get set vr =
-                //printfn $"{s}"
+            let appl get set vr =
                 match expr |> get with
                 | Some m -> vr |> set m
                 | None -> vr
@@ -3000,9 +2999,9 @@ module Variable =
             | ValSet vs -> y |> setValueSet vs
             | _ ->
                 y
-                |> appl "incr" getIncr setIncr
-                |> appl "min" getMin setMin
-                |> appl "max" getMax setMax
+                |> appl getIncr setIncr
+                |> appl getMin setMin
+                |> appl getMax setMax
 
 
         module Operators =
@@ -3015,8 +3014,6 @@ module Variable =
 
             let inline (^-) vr1 vr2 = calc false (-) (vr1, vr2)
 
-            let inline (^<-) vr1 vr2 = applyExpr vr1 vr2
-
 
             let inline (@*) vr1 vr2 = calc true (*) (vr1, vr2)
 
@@ -3093,14 +3090,11 @@ module Variable =
 
     /// Apply a `ValueRange` **vr** to
     /// `Variable` **v**.
-    let setValueRange onlyMinIncrMax var vr =
-        let op =
-            if onlyMinIncrMax then (@<-) else (^<-)
-
+    let setValueRange var vr =
         try
             { var with
                 Values =
-                    (var |> get).Values |> op <| vr
+                    (var |> get).Values @<- vr
             }
 
         with
@@ -3239,8 +3233,6 @@ module Variable =
 
         let inline (^-) vr1 vr2 = calc (^-) (vr1, vr2)
 
-        let inline (^<-) vr1 vr2 = vr2 |> getValueRange |> setValueRange false vr1
-
 
         let inline (@*) vr1 vr2 = calc (@*) (vr1, vr2)
 
@@ -3250,7 +3242,7 @@ module Variable =
 
         let inline (@-) vr1 vr2 = calc (@-) (vr1, vr2)
 
-        let inline (@<-) vr1 vr2 = vr2 |> getValueRange |> setValueRange true vr1
+        let inline (@<-) vr1 vr2 = vr2 |> getValueRange |> setValueRange vr1
 
 
         /// Constant 1
diff --git a/tests/Informedica.GenSolver.Tests/Tests.fs b/tests/Informedica.GenSolver.Tests/Tests.fs
index 1ebc250..3a37cf9 100644
--- a/tests/Informedica.GenSolver.Tests/Tests.fs
+++ b/tests/Informedica.GenSolver.Tests/Tests.fs
@@ -128,7 +128,7 @@ module TestSolver =
 
     let setProp n p eqs =
         let n = n |> Name.createExc
-        match eqs |> Api.setVariableValues true n p with
+        match eqs |> Api.setVariableValues n p with
         | Some var ->
             eqs
             |> List.map (fun e ->