diff --git a/descriptor.py b/descriptor.py
new file mode 100644
index 00000000..67f940f1
--- /dev/null
+++ b/descriptor.py
@@ -0,0 +1,270 @@
+from pynxtools.dataconverter.nexus_tree import NexusNode
+
+from pynxtools.dataconverter.helpers import generate_template_from_nxdl
+from pynxtools.dataconverter.nexus_tree import *
+from pynxtools.dataconverter.template import Template
+from pynxtools.dataconverter.nexus_tree import generate_tree_from
+
+# import template
+from pynxtools.dataconverter.template import Template
+import copy
+
+
+## Template class
+## ==========================================
+class KeyProperty:
+    """
+    A class to represent the key of the Template class.
+
+    The class is intended to have private attributes:
+        NXtype: group, field, or attribute
+        NXdataType: INT, FLOAT, according to the nexus data type
+        NXunits: NX_LENGTH, NX_TIME, NX_CURRENT, or m, power, etc.
+    """
+
+    prop_name = None
+    _prop_name = None
+
+    def __set_name__(self, owner, name):
+        """Set the name of the property."""
+        self.prop_name = name
+        self._prop_name = f"_{name}"
+
+    def __get__(self, instance, owner):
+        """Get the value of the property."""
+        return getattr(instance, self._prop_name, None)
+
+    def __set__(self, instance, value):
+        """Set the value of the property."""
+        if not isinstance(value, KeyObject):
+            raise TypeError(f"Expected KeyObject, got {type(value)}")
+        setattr(instance, self._prop_name, value)
+
+    # def __setitem__(self, key, value):
+    #     """Set the value of the property."""
+    #     if not isinstance(value, KeyObject):
+    #         raise TypeError(f"Expected KeyObject, got {type(value)}")
+
+    #     setattr(self, key, value)
+
+class KeyObject:
+    """
+    A class to represent the key of the Template class.
+
+    The class is intended to have private attributes:
+        NXtype: group, field, or attribute
+        NXdataType: INT, FLOAT, according to the nexus data type
+        NXunits: NX_LENGTH, NX_TIME, NX_CURRENT, or m, power, etc.
+    """
+
+    nx_name = KeyProperty()
+    nx_class = KeyProperty()
+    nx_units = KeyProperty()
+    nx_dtype = KeyProperty()
+    # None  # data  type
+    nx_name_type = KeyProperty()
+    nx_optionality = KeyProperty()
+    value = KeyProperty()
+    nx_node = None
+
+    def __init__(
+        self,
+        nx_node,
+        concept_value=None,
+    ):
+        # TODO remove the node
+        self.nx_node = nx_node
+        self.value = concept_value
+
+        if self.nx_node.type == "group":
+            self.nx_class = self.nx_node.nx_class
+            self.nx_dtype = None
+        elif self.nx_node.type in ("field", "attribute"):
+            self.nx_class = None
+            self.nx_dtype = self.nx_node.nx_dtype
+            if units := getattr(self.nx_node, "unit", None):
+                self._nx_units = units
+        # elif self.nx_node.type == "choice":
+        # Not implemented yet
+        self.nx_name = self.nx_node.name
+        self.nx_name_type = self.nx_node.name_type
+        self.nx_optionality = self.nx_node.optionality
+
+    def __repr__(self):
+        """Returns a unique string representation for the KeyObject object."""
+        return self.value
+
+    def __eq__(self, value):
+        self.value = value
+
+    def __getattr__(self, name):
+        """Handles how attributes are accessed from the KeyObject object."""
+        if name in self.__dict__:
+            return getattr(self, name)
+        else:
+            raise AttributeError(
+                f"'{self.__class__.__name__}' object has no attribute '{name}'"
+            )
+
+    def __setattr__(self, name, value):
+        """Handles how attributes are set within the KeyObject object."""
+        if name in self.__dict__:
+            setattr(self, name, value)
+        else:
+            raise AttributeError(
+                f"'{self.__class__.__name__}' object has no attribute '{name}'"
+            )
+
+
+class DescriptedTemplate(dict):
+    """
+    A Template object to control and separate template paths according to optionality.
+    """
+
+    def __init__(self, template=None, **kwargs):
+        super().__init__(**kwargs)
+        if isinstance(template, Template):
+            self.optional: dict = copy.deepcopy(template["optional"])
+            self.recommended: dict = copy.deepcopy(template["recommended"])
+            self.required: dict = copy.deepcopy(template["required"])
+            self.undocumented: dict = copy.deepcopy(template["undocumented"])
+            self.optional_parents: list = copy.deepcopy(template["optional_parents"])
+            # self.lone_groups: dict = copy.deepcopy(template["lone_groups"])
+        else:
+            self.optional: dict = {}  # type: ignore[no-redef]
+            self.recommended: dict = {}  # type: ignore[no-redef]
+            self.required: dict = {}  # type: ignore[no-redef]
+            self.undocumented: dict = {}  # type: ignore[no-redef]
+            self.optional_parents: list = []  # type: ignore[no-redef]
+            self.lone_groups: list = []  # type: ignore[no-redef, assignment]
+            if isinstance(template, dict):
+                self.undocumented: dict = copy.deepcopy(template)  # type: ignore[no-redef]
+
+        # self.overwrite_keys = overwrite_keys
+
+    def get_accumulated_dict(self):
+        """Returns a dictionary of all the optionalities merged into one."""
+        return {
+            **self.optional,
+            **self.recommended,
+            **self.required,
+            **self.undocumented,
+        }
+
+    def __repr__(self):
+        """Returns a unique string representation for the Template object."""
+        return self.get_accumulated_dict().__repr__()
+
+    def __setitem__(self, key, value):
+        """Handles how values are set within the Template object."""
+        if isinstance(value, dict):
+            pass
+        elif isinstance(value, KeyObject):
+            # If value is an KeyObject, store it in the dictionary
+            opt = None
+            if not (opt := value.nx_optionality):
+                self.optional[key] = value
+            elif opt == "recommended":
+                self.recommended[key] = value
+            elif opt == "required":
+                self.required[key] = value
+            else:  # opt == "undocumented"
+                self.undocumented[key] = value
+            raise KeyError(
+                f"Node does not have proper optionality value."
+                f"Has {value.nx_optionality} but should be one"
+                f" of [optional, recommended, required, undocumented]"
+            )
+        else:
+            self.undocumented[key] = value
+        # return super().__setitem__(key, value)
+
+    def __getitem__(self, key):
+        """Handles how values are accessed from the Template object."""
+        # Try setting item in all else throw error. Does not append to default.
+        if key in self.required:
+            return self.required[key]
+        elif key in self.optional:
+            return self.optional[key]
+        elif key in self.recommended:
+            return self.recommended[key]
+        elif key in self.undocumented:
+            return self.undocumented[key]
+        if key in ("optional", "recommended", "required", "undocumented"):
+            return getattr(self, key)
+
+        # if key in ("required", "optional", "recommended", "undocumented"):
+        #     return self.get_optionality(key)
+        raise KeyError(
+            "Only paths starting with '/' or one of [optional_parents, "
+            "lone_groups, required, optional, recommended, undocumented] can be used."
+        )
+
+
+# Create Template from NeXusNode Tree
+def add_template_key_from(nx_node, template, parent_path=""):
+    key = None
+    unit = None
+    if nx_node.type == "attribute":
+        leaf_part = (
+            f"{nx_node.name}[{nx_node.name}]" if nx_node.variadic else nx_node.name
+        )
+        key = f"{parent_path}/@{leaf_part}"
+    elif nx_node.type == "field":
+        leaf_part = (
+            f"{nx_node.name}[{nx_node.name}]" if nx_node.variadic else nx_node.name
+        )
+        key = f"{parent_path}/{leaf_part}"
+        if hasattr(nx_node, "unit") and nx_node.unit:
+            unit = f"{key}/@units"
+    elif nx_node.type == "group":
+        leaf_part = f"{nx_node.name}[{nx_node.name}]"
+        key = f"{parent_path}/{leaf_part}"
+    if key:
+        template[nx_node.optionality][key] = KeyObject(nx_node)
+    if unit:
+        template[nx_node.optionality][unit] = nx_node.unit
+    return key
+
+
+# TODO: appdef tree
+def build_template_from_nexus_tree(appdef_root, template, parent_path=""):
+    """
+    Build a template from the nexus tree.
+    """
+    for child in appdef_root.children:
+        key = add_template_key_from(child, template, parent_path)
+        if not key:
+            continue
+        build_template_from_nexus_tree(child, template, key)
+
+
+# template = Template()
+# build_template_from_nexus_tree(spmT, template)
+# template_old = Template()
+
+# root, _ = get_nxdl_root_and_path(spm_appdef)
+# generate_template_from_nxdl(
+#     root=root,
+#     template=template_old,
+# )
+# print(' #### check optional missing keys')
+# template_ = template
+# template_old_ = template_old
+# def check_missing():
+#     for key, _ in template_['optional'].items():
+#         if key not in template_old_['optional']:
+#             print(f"OPTIONAL Missing key in template_old: {key}")
+#     print(' #### check required missing keys')
+#     for key, _ in template_['required'].items():
+#         if key not in template_old_['required']:
+#             print(f"REQUIRED: Missing key in template_old: {key}")
+
+tempate = DescriptedTemplate()
+spm = "NXspm"
+
+spmT = generate_tree_from(spm)
+
+build_template_from_nexus_tree(appdef_root=spmT, template=tempate)
+
+xx = "hello"
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