diff --git a/mathics/builtin/functional/application.py b/mathics/builtin/functional/application.py
index 4a9683de8..e41a6138d 100644
--- a/mathics/builtin/functional/application.py
+++ b/mathics/builtin/functional/application.py
@@ -4,26 +4,28 @@
 Function Application
 """
 
-# This tells documentation how to sort this module
-sort_order = "mathics.builtin.function-application"
-
-
 from itertools import chain
 
 import sympy
 
 from mathics.core.atoms import Integer, Integer1
 from mathics.core.attributes import A_HOLD_ALL, A_N_HOLD_ALL, A_PROTECTED
-from mathics.core.builtin import Builtin, PostfixOperator, SympyFunction
+from mathics.core.builtin import Builtin, PostfixOperator, PrefixOperator, SympyFunction
 from mathics.core.convert.sympy import SymbolFunction
 from mathics.core.evaluation import Evaluation
 from mathics.core.expression import Expression
 from mathics.core.symbols import Symbol, sympy_slot_prefix
 from mathics.core.systemsymbols import SymbolSlot
 
+# This tells documentation how to sort this module
+sort_order = "mathics.builtin.function-application"
+
 
 class Function(PostfixOperator, SympyFunction):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/Function.html</url>
+
     <dl>
       <dt>'Function[$body$]'
       <dt>'$body$ &'
@@ -164,8 +166,11 @@ def to_sympy(self, expr: Expression, **kwargs):
             raise NotImplementedError
 
 
-class Slot(SympyFunction):
+class Slot(SympyFunction, PrefixOperator):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/Slot.html</url>
+
     <dl>
       <dt>'#$n$'
       <dd>represents the $n$th argument to a pure function.
@@ -190,6 +195,9 @@ class Slot(SympyFunction):
     """
 
     attributes = A_N_HOLD_ALL | A_PROTECTED
+
+    operator = "#"  # FIXME generate this automatically
+
     rules = {
         "Slot[]": "Slot[1]",
         "MakeBoxes[Slot[n_Integer?NonNegative],"
@@ -204,8 +212,12 @@ def to_sympy(self, expr: Expression, **kwargs):
         return sympy.Symbol(f"{sympy_slot_prefix}{index.get_int_value()}")
 
 
-class SlotSequence(Builtin):
+class SlotSequence(PrefixOperator, Builtin):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/SlotSequence.html</url>
+
+
     <dl>
       <dt>'##'
       <dd>is the sequence of arguments supplied to a pure function.
@@ -225,6 +237,8 @@ class SlotSequence(Builtin):
 
     attributes = A_N_HOLD_ALL | A_PROTECTED
 
+    operator = "##"  # FIXME generate this automatically
+
     rules = {
         "SlotSequence[]": "SlotSequence[1]",
         "MakeBoxes[SlotSequence[n_Integer?Positive],"
diff --git a/mathics/builtin/functional/apply_fns_to_lists.py b/mathics/builtin/functional/apply_fns_to_lists.py
index f6dbbffd4..8ab4650fb 100644
--- a/mathics/builtin/functional/apply_fns_to_lists.py
+++ b/mathics/builtin/functional/apply_fns_to_lists.py
@@ -29,6 +29,10 @@
 
 class Apply(InfixOperator):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/Apply.html</url>
+
+
     <dl>
       <dt>'Apply[$f$, $expr$]'
 
@@ -67,6 +71,8 @@ class Apply(InfixOperator):
     summary_text = "apply a function to a list, at specified levels"
     grouping = "Right"
 
+    operator = "@@"  # FIXME generate this automatically
+
     options = {
         "Heads": "False",
     }
@@ -100,6 +106,9 @@ def callback(level):
 
 class Map(InfixOperator):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/Map.html</url>
+
     <dl>
       <dt>'Map[$f$, $expr$]' or '$f$ /@ $expr$'
       <dd>applies $f$ to each part on the first level of $expr$.
@@ -155,6 +164,9 @@ def callback(level):
 
 class MapAt(Builtin):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/MapAt.html</url>
+
     <dl>
       <dt>'MapAt[$f$, $expr$, $n$]'
       <dd>applies $f$ to the element at position $n$ in $expr$. If $n$ is negative, the position is counted from the end.
@@ -211,6 +223,9 @@ def eval(self, f, expr, args, evaluation: Evaluation):
 
 class MapIndexed(Builtin):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/MapIndexed.html</url>
+
     <dl>
       <dt>'MapIndexed[$f$, $expr$]'
       <dd>applies $f$ to each part on the first level of $expr$, including the part positions in the call to $f$.
@@ -280,6 +295,9 @@ def callback(level, pos: Iterable):
 
 class MapThread(Builtin):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/MapThread.html</url>
+
     <dl>
       <dt>'MapThread[$f$, {{$a1$, $a2$, ...}, {$b1$, $b2$, ...}, ...}]
       <dd>returns '{$f$[$a1$, $b1$, ...], $f$[$a2$, $b2$, ...], ...}'.
@@ -367,6 +385,9 @@ def walk(args, depth=0):
 
 class Scan(Builtin):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/Scan.html</url>
+
     <dl>
       <dt>'Scan[$f$, $expr$]'
       <dd>applies $f$ to each element of $expr$ and returns 'Null'.
@@ -417,6 +438,9 @@ def callback(level):
 
 class Thread(Builtin):
     """
+    <url>:WMA link:
+      https://reference.wolfram.com/language/ref/Thread.html</url>
+
     <dl>
       <dt>'Thread[$f$[$args$]]'
       <dd>threads $f$ over any lists that appear in $args$.