diff --git a/flamapy/metamodels/fm_metamodel/transformations/clafer_writer.py b/flamapy/metamodels/fm_metamodel/transformations/clafer_writer.py
index ab331d1..1591980 100644
--- a/flamapy/metamodels/fm_metamodel/transformations/clafer_writer.py
+++ b/flamapy/metamodels/fm_metamodel/transformations/clafer_writer.py
@@ -1,4 +1,5 @@
 import re
+import string
 from enum import Enum
 from typing import Any, Optional
 
@@ -152,4 +153,8 @@ def parse_type_value(value: Any) -> str:
 
 
 def safename(name: str) -> str:
-    return f'"{name}"' if ' ' in name else name
+    return f'"{name}"' if any(char in name for char in safecharacters()) else name
+
+
+def safecharacters() -> str:
+    return string.ascii_letters + string.digits + '_'
diff --git a/flamapy/metamodels/fm_metamodel/transformations/featureide_writer.py b/flamapy/metamodels/fm_metamodel/transformations/featureide_writer.py
index 94dbdcd..9f9f1d2 100644
--- a/flamapy/metamodels/fm_metamodel/transformations/featureide_writer.py
+++ b/flamapy/metamodels/fm_metamodel/transformations/featureide_writer.py
@@ -1,3 +1,4 @@
+import string
 from xml.etree import ElementTree
 from xml.etree.ElementTree import Element
 from xml.dom import minidom
@@ -139,4 +140,8 @@ def prettify(xml: str) -> bytes:
 
 
 def safename(name: str) -> str:
-    return f'"{name}"' if ' ' in name else name
+    return f'"{name}"' if any(char in name for char in safecharacters()) else name
+
+
+def safecharacters() -> str:
+    return string.ascii_letters + string.digits + '_'
diff --git a/flamapy/metamodels/fm_metamodel/transformations/glencoe_writer.py b/flamapy/metamodels/fm_metamodel/transformations/glencoe_writer.py
index 5f7450d..247b11b 100644
--- a/flamapy/metamodels/fm_metamodel/transformations/glencoe_writer.py
+++ b/flamapy/metamodels/fm_metamodel/transformations/glencoe_writer.py
@@ -1,4 +1,5 @@
 import json
+import string
 from typing import Any
 
 from flamapy.core.models.ast import Node, ASTOperation
@@ -106,4 +107,8 @@ def _get_ctc_info(ast_node: Node) -> dict[str, Any]:
 
 
 def safename(name: str) -> str:
-    return f'"{name}"' if ' ' in name else name
+    return f'"{name}"' if any(char in name for char in safecharacters()) else name
+
+
+def safecharacters() -> str:
+    return string.ascii_letters + string.digits + '_'
diff --git a/flamapy/metamodels/fm_metamodel/transformations/json_writer.py b/flamapy/metamodels/fm_metamodel/transformations/json_writer.py
index 8e5ea5e..3392e22 100644
--- a/flamapy/metamodels/fm_metamodel/transformations/json_writer.py
+++ b/flamapy/metamodels/fm_metamodel/transformations/json_writer.py
@@ -1,4 +1,5 @@
 import json
+import string
 from enum import Enum
 from typing import Any, Dict, List
 
@@ -126,4 +127,8 @@ def get_ctc_info(ast_node: Node) -> Dict[str, Any]:
 
 
 def safename(name: str) -> str:
-    return f'"{name}"' if ' ' in name else name
\ No newline at end of file
+    return f'"{name}"' if any(char in name for char in safecharacters()) else name
+
+
+def safecharacters() -> str:
+    return string.ascii_letters + string.digits + '_'
diff --git a/flamapy/metamodels/fm_metamodel/transformations/splot_writer.py b/flamapy/metamodels/fm_metamodel/transformations/splot_writer.py
index e3133d3..448f619 100644
--- a/flamapy/metamodels/fm_metamodel/transformations/splot_writer.py
+++ b/flamapy/metamodels/fm_metamodel/transformations/splot_writer.py
@@ -1,3 +1,5 @@
+import string
+
 from flamapy.core.transformations import ModelToText
 from flamapy.metamodels.fm_metamodel.models import (
     FeatureModel,
@@ -83,4 +85,8 @@ def add_constraints(constraints: list[Constraint]) -> list[str]:
 
 
 def safename(name: str) -> str:
-    return f'"{name}"' if ' ' in name else name
+    return f'"{name}"' if any(char in name for char in safecharacters()) else name
+
+
+def safecharacters() -> str:
+    return string.ascii_letters + string.digits + '_'
diff --git a/flamapy/metamodels/fm_metamodel/transformations/uvl_reader.py b/flamapy/metamodels/fm_metamodel/transformations/uvl_reader.py
index 51c6a06..020b985 100644
--- a/flamapy/metamodels/fm_metamodel/transformations/uvl_reader.py
+++ b/flamapy/metamodels/fm_metamodel/transformations/uvl_reader.py
@@ -83,7 +83,7 @@ def process_attributes(
             constraint_attribute = attribute_context.constraintAttribute()
 
             if value_attribute:
-                key = value_attribute.key().getText()
+                key = value_attribute.key().getText().replace('"', '')
                 if value_attribute.value():
                     value = self.process_value(value_attribute.value())
                 else:
@@ -96,7 +96,7 @@ def process_attributes(
             else:
                 # Handle unexpected case
                 raise ValueError(
-                    f"Unknown attribute type for: {attribute_context.getText()}"
+                    f"Unknown attribute type for: {attribute_context.getText().replace('"', '')}"
                 )
 
             attributes_dict[key] = value
diff --git a/flamapy/metamodels/fm_metamodel/transformations/uvl_writer.py b/flamapy/metamodels/fm_metamodel/transformations/uvl_writer.py
index bb586e1..18203e2 100644
--- a/flamapy/metamodels/fm_metamodel/transformations/uvl_writer.py
+++ b/flamapy/metamodels/fm_metamodel/transformations/uvl_writer.py
@@ -1,4 +1,5 @@
 import re
+import string
 
 from flamapy.core.models.ast import ASTOperation
 from flamapy.core.transformations import ModelToText
@@ -135,4 +136,8 @@ def serialize_constraint(ctc: Constraint) -> str:
 
 
 def safename(name: str) -> str:
-    return f'"{name}"' if ' ' in name else name
+    return f'"{name}"' if any(char in name for char in safecharacters()) else name
+
+
+def safecharacters() -> str:
+    return string.ascii_letters + string.digits + '_'