diff --git a/ComputingTasks.cc b/ComputingTasks.cc
index f750b9b6..ae5a6f22 100644
--- a/ComputingTasks.cc
+++ b/ComputingTasks.cc
@@ -2600,7 +2600,7 @@ SvarIdentificationStatement::writeJsonOutput(ostream &output) const
           output << "{"
                  << "\"equation_number\": " << it->equation << ", "
                  << "\"restriction_number\": " << it->restriction_nbr << ", "
-                 << "\"variable\": " << symbol_table.getName(it->variable) << ", "
+                 << "\"variable\": \"" << symbol_table.getName(it->variable) << "\", "
                  << "\"expression\": \"";
           it->value->writeOutput(output);
           output << "\"}";
diff --git a/ExprNode.cc b/ExprNode.cc
index b5b9d4dd..5cc0298b 100644
--- a/ExprNode.cc
+++ b/ExprNode.cc
@@ -5610,15 +5610,15 @@ ExternalFunctionNode::writeJsonExternalFunctionOutput(vector<string> &efout,
 
       stringstream ef;
       ef << "{\"external_function\": {"
-         << "\"output\": \"TEF_" << indx << "\"";
+         << "\"external_function_term\": \"TEF_" << indx << "\"";
 
       if (symb_id == first_deriv_symb_id)
-        ef << ", \"output_d\": \"TEFD_" << indx << "\"";
+        ef << ", \"external_function_term_d\": \"TEFD_" << indx << "\"";
 
       if (symb_id == second_deriv_symb_id)
-        ef << ", \"output_dd\": \"TEFDD_" << indx << "\"";
+        ef << ", \"external_function_term_dd\": \"TEFDD_" << indx << "\"";
 
-      ef << ", \"function\": \"" << datatree.symbol_table.getName(symb_id) << "(";
+      ef << ", \"value\": \"" << datatree.symbol_table.getName(symb_id) << "(";
       writeJsonExternalFunctionArguments(ef, temporary_terms, tef_terms);
       ef << ")\"}}";
       efout.push_back(ef.str());
@@ -5944,17 +5944,17 @@ FirstDerivExternalFunctionNode::writeJsonExternalFunctionOutput(vector<string> &
   stringstream ef;
   if (first_deriv_symb_id == eExtFunNotSet)
     ef << "{\"first_deriv_external_function\": {"
-       << "\"output\": \"TEFD_fdd_" << getIndxInTefTerms(symb_id, tef_terms) << "_" << inputIndex << "\""
+       << "\"external_function_term\": \"TEFD_fdd_" << getIndxInTefTerms(symb_id, tef_terms) << "_" << inputIndex << "\""
        << ", \"analytic_derivative\": false"
        << ", \"wrt\": " << inputIndex
-       << ", \"function\": \"" << datatree.symbol_table.getName(symb_id) << "(";
+       << ", \"value\": \"" << datatree.symbol_table.getName(symb_id) << "(";
   else
     {
       tef_terms[make_pair(first_deriv_symb_id, arguments)] = (int) tef_terms.size();
       ef << "{\"first_deriv_external_function\": {"
-         << "\"output\": \"TEFD_def_" << getIndxInTefTerms(first_deriv_symb_id, tef_terms)
+         << "\"external_function_term\": \"TEFD_def_" << getIndxInTefTerms(first_deriv_symb_id, tef_terms) << "\""
          << ", \"analytic_derivative\": true"
-         << ", \"function\": \"" << datatree.symbol_table.getName(first_deriv_symb_id) << "(";
+         << ", \"value\": \"" << datatree.symbol_table.getName(first_deriv_symb_id) << "(";
     }
 
   writeJsonExternalFunctionArguments(ef, temporary_terms, tef_terms);
@@ -6303,18 +6303,18 @@ SecondDerivExternalFunctionNode::writeJsonExternalFunctionOutput(vector<string>
   stringstream ef;
   if (second_deriv_symb_id == eExtFunNotSet)
     ef << "{\"second_deriv_external_function\": {"
-       << "\"output\": \"TEFDD_fdd_" << getIndxInTefTerms(symb_id, tef_terms) << "_" << inputIndex1 << "_" << inputIndex2 << "\""
+       << "\"external_function_term\": \"TEFDD_fdd_" << getIndxInTefTerms(symb_id, tef_terms) << "_" << inputIndex1 << "_" << inputIndex2 << "\""
        << ", \"analytic_derivative\": false"
        << ", \"wrt1\": " << inputIndex1
        << ", \"wrt2\": " << inputIndex2
-       << ", \"function\": \"" << datatree.symbol_table.getName(symb_id) << "(";
+       << ", \"value\": \"" << datatree.symbol_table.getName(symb_id) << "(";
   else
     {
       tef_terms[make_pair(second_deriv_symb_id, arguments)] = (int) tef_terms.size();
       ef << "{\"second_deriv_external_function\": {"
-         << "\"output\": \"TEFDD_def_" << getIndxInTefTerms(second_deriv_symb_id, tef_terms)
+         << "\"external_function_term\": \"TEFDD_def_" << getIndxInTefTerms(second_deriv_symb_id, tef_terms) << "\""
          << ", \"analytic_derivative\": true"
-         << ", \"function\": \"" << datatree.symbol_table.getName(second_deriv_symb_id) << "(";
+         << ", \"value\": \"" << datatree.symbol_table.getName(second_deriv_symb_id) << "(";
     }
 
   writeJsonExternalFunctionArguments(ef, temporary_terms, tef_terms);
diff --git a/ModelTree.cc b/ModelTree.cc
index 3e2b7395..a2cc7df3 100644
--- a/ModelTree.cc
+++ b/ModelTree.cc
@@ -1334,7 +1334,8 @@ ModelTree::writeJsonTemporaryTerms(const temporary_terms_t &tt, const temporary_
           output << ", ";
         output << "{\"temporary_term\": \"";
         (*it)->writeJsonOutput(output, tt, tef_terms);
-        output << " = ";
+        output << "\""
+               << ", \"value\": \"";
         (*it)->writeJsonOutput(output, tt2, tef_terms);
         output << "\"}" << endl;
         wrote_term = true;
@@ -1567,12 +1568,15 @@ ModelTree::writeJsonModelLocalVariables(ostream &output, deriv_node_temp_terms_t
   for (set<int>::const_iterator it = used_local_vars.begin();
        it != used_local_vars.end(); ++it)
     {
+      if (it != used_local_vars.begin())
+        output << ", ";
       int id = *it;
       expr_t value = local_variables_table.find(id)->second;
 
       /* We append underscores to avoid name clashes with "g1" or "oo_" (see
          also VariableNode::writeOutput) */
-      output << "{\"" << symbol_table.getName(id) << "__ = ";
+      output << "{\"variable\": \"" << symbol_table.getName(id) << "__\""
+             << ", \"value\": \"";
       value->writeJsonOutput(output, tt, tef_terms);
       output << "\"}" << endl;
     }