diff --git a/src/DOI/aliases.jl b/src/DOI/aliases.jl
index 230669a..57f3be4 100644
--- a/src/DOI/aliases.jl
+++ b/src/DOI/aliases.jl
@@ -21,9 +21,13 @@ const ALG_CONS = OrderedDict{
     Tuple{NDF,EQ64},
 }
 
+# const LINKAGES = OrderedDict{
+#     MOI.ConstraintIndex{DOI.Linkage{DYN_VAR},EQ64},
+#     Tuple{DOI.Linkage{DYN_VAR},EQ64}
+# }
 const LINKAGES = OrderedDict{
-    MOI.ConstraintIndex{DOI.Linkage{DYN_VAR},EQ64},
-    Tuple{DOI.Linkage{DYN_VAR},EQ64}
+    MOI.ConstraintIndex,             # Loosen key to generic ConstraintIndex
+    Tuple{DOI.Linkage,EQ64}          # Loosen value to generic DOI.Linkage
 }
 
 const OBJ = DOI.Bolza{NBF,DOI.MultiPhaseIntegral{NDF}}
diff --git a/src/DOI/ingredients.jl b/src/DOI/ingredients.jl
index 9964974..a58c72f 100644
--- a/src/DOI/ingredients.jl
+++ b/src/DOI/ingredients.jl
@@ -151,10 +151,10 @@ end
 
 # Dynamic variable boundaries
 
-MOI.supports_constraint(::Optimizer, ::DOI.Initial{DYN_VAR}, ::IV64) = true
-MOI.supports_constraint(::Optimizer, ::DOI.Final{DYN_VAR},   ::IV64) = true
+MOI.supports_constraint(::Optimizer, ::DOI.Initial{DYN_VAR}, ::EQ64) = true
+MOI.supports_constraint(::Optimizer, ::DOI.Final{DYN_VAR},   ::EQ64) = true
 
-function MOI.add_constraint(model::Optimizer, dyn_var_initial::DOI.Initial{DYN_VAR}, set::IV64)
+function MOI.add_constraint(model::Optimizer, dyn_var_initial::DOI.Initial{DYN_VAR}, set::EQ64)
 
     dyn_var = dyn_var_initial.dyn_fun
 
@@ -163,15 +163,15 @@ function MOI.add_constraint(model::Optimizer, dyn_var_initial::DOI.Initial{DYN_V
     phase = DOI.phase_index(dyn_var_initial.dyn_fun)
     
     if haskey(model.dyn_var_initials[phase], dyn_var)
-        throw(MOI.AddConstraintNotAllowed{typeof(dyn_var_initial),IV64}("Initial value already set."))
+        throw(MOI.AddConstraintNotAllowed{typeof(dyn_var_initial),EQ64}("Initial value already set."))
     end
 
    model.dyn_var_initials[phase][dyn_var] = set
 
-    return MOI.ConstraintIndex{DOI.Initial{DYN_VAR},IV64}(dyn_var.value)
+    return MOI.ConstraintIndex{DOI.Initial{DYN_VAR},EQ64}(dyn_var.value)
 end
 
-function MOI.add_constraint(model::Optimizer, dyn_var_final::DOI.Final{DYN_VAR}, set::IV64)
+function MOI.add_constraint(model::Optimizer, dyn_var_final::DOI.Final{DYN_VAR}, set::EQ64)
 
     dyn_var = dyn_var_final.dyn_fun
 
@@ -180,12 +180,12 @@ function MOI.add_constraint(model::Optimizer, dyn_var_final::DOI.Final{DYN_VAR},
     phase = DOI.phase_index(dyn_var_final.dyn_fun)
     
     if haskey(model.dyn_var_finals[phase], dyn_var)
-        throw(MOI.AddConstraintNotAllowed{typeof(dyn_var_final),IV64}("Final value already set."))
+        throw(MOI.AddConstraintNotAllowed{typeof(dyn_var_final),EQ64}("Final value already set."))
     end
 
     model.dyn_var_finals[phase][dyn_var] = set
 
-    return MOI.ConstraintIndex{DOI.Final{DYN_VAR},IV64}(dyn_var.value)
+    return MOI.ConstraintIndex{DOI.Final{DYN_VAR},EQ64}(dyn_var.value)
 end
 
 
@@ -210,10 +210,11 @@ end
 
 # Linkages
 
-MOI.supports_constraint(::Optimizer, ::Type{DOI.Linkage{DYN_VAR}}, ::EQ64) = true
+MOI.supports_constraint(::Optimizer, ::DOI.Linkage{<:Union{PHS,DYN_VAR}}, ::EQ64) = true
 
-function MOI.add_constraint(model::Optimizer, linkage::DOI.Linkage{DYN_VAR}, set::EQ64)
+function MOI.add_constraint(model::Optimizer, linkage::DOI.Linkage{T}, set::EQ64) where T<:Union{PHS,DYN_VAR}
 
+    
     _throw_if_invalid_index(model, linkage.dyn_fun_final)
     _throw_if_invalid_index(model, linkage.dyn_fun_initial)
 
diff --git a/src/intervals.jl b/src/intervals.jl
index 9862f2d..2d05096 100644
--- a/src/intervals.jl
+++ b/src/intervals.jl
@@ -36,7 +36,7 @@ struct FixedIntervals <: AbstractIntervals
 
     function FixedIntervals(
         number::Integer;
-        points::Vector{<:Real}=collect(range(0.0, 1.0, number + 1)),
+        points::Vector{<:Real}=collect(range(0.0, 1.0, length = number + 1)),
     )
         if !(number ≥ 1)
             throw(DomainError(number, "Please ensure number ≥ 1."))
@@ -128,7 +128,7 @@ struct FlexibleIntervals <: AbstractIntervals
     function FlexibleIntervals(
         number::Integer,
         flexibility::Real;
-        points::Vector{Float64}=collect(range(0.0, 1.0, number + 1)),
+        points::Vector{Float64}=collect(range(0.0, 1.0, length = number + 1)),
     )
         if !(number ≥ 2)
             throw(DomainError(number, "Please ensure number ≥ 2."))