code: function () {
                      var key, value;
                      parserInput.save();
                      key = parserInput.$re(/^\w+(?=\s?=)/i);
                      if (!key) {
                          parserInput.restore();
                          return;
                      }
                      if (!parserInput.$char('=')) {
                          parserInput.restore();
                          return;
                      }
                      value = parsers.entity();
                      if (value) {
                          parserInput.forget();
                          return new(tree.Assignment)(key, value);
                      } else {
                          parserInput.restore();
                      }
                  }
docs: Assignments are argument entities for calls. They are present in ie filter properties as shown below.  filter: progid:DXImageTransform.Microsoft.Alpha( *opacity=50* )