diff --git a/content/09_annexes/checker-rules.adoc b/content/09_annexes/checker-rules.adoc
index 81a34cc2..34dd0f69 100644
--- a/content/09_annexes/checker-rules.adoc
+++ b/content/09_annexes/checker-rules.adoc
@@ -174,13 +174,13 @@ Description:: A temperature in Kelvin (K) shall not be below 0.
 
 UID:: asam.net:xom-mat:1.0.0:xompt.real_part_ior_valid_range
 
-Description:: The real part of index of refraction (refractive index n) shall not be below 0.
+Description:: The real part of the index of refraction (refractive index n) shall not be below 0.
 
 ==== imaginary_part_ior_valid_range
 
 UID:: asam.net:xom-mat:1.0.0:xompt.imaginary_part_ior_valid_range
 
-Description:: The imaginary part of index (extinction coefficient k) of refraction shall not be below 0 (= perfect transparent material).
+Description:: The imaginary part of the index (extinction coefficient k) of refraction shall not be below 0 (= perfect transparent material).
 
 ==== humidity_valid_range
 
@@ -192,19 +192,25 @@ Description:: The humidity in percent (%) shall be within the range of 0 to 100.
 
 UID:: asam.net:xom-mat:1.0.0:xompt.real_part_permeability_valid_range
 
-Description:: The real part of permeability shall be within the range of 1.256637e-06 to 1.256637 (µ~0~ to µ~0~ x 10e06).
+Description:: The real part of the relative permeability shall not be below 1.
 
 ==== imaginary_part_permeability_valid_range
 
-UID:: asam.net:xom-mat:1.0.0:xompt.real_part_permeability_valid_range
+UID:: asam.net:xom-mat:1.0.0:xompt.imaginary_part_permeability_valid_range
+
+Description:: The imaginary part of the relative permeability shall not be below 0.
+
+==== real_part_permittivity_valid_range
+
+UID:: asam.net:xom-mat:1.0.0:xompt.real_part_permittivity_valid_range
 
-Description:: The imaginary part of permeability shall not be below 0.
+Description:: The real part of the relative permittivity shall not be below 1.
 
 ==== imaginary_part_permittivity_valid_range
 
 UID:: asam.net:xom-mat:1.0.0:xompt.imaginary_part_permitivity_valid_range
 
-Description:: The imaginary part of permittivity shall not be below 0.
+Description:: The imaginary part of the relative permittivity shall not be below 0.
 
 ==== incident_elevation_angle_valid_range
 
diff --git a/schemas/material_emp_schema.json b/schemas/material_emp_schema.json
index ddd90238..5c54d4fb 100644
--- a/schemas/material_emp_schema.json
+++ b/schemas/material_emp_schema.json
@@ -103,28 +103,28 @@
                             "number",
                             "null"
                         ],
-                        "description": "Real part of complex permeability of material."
+                        "description": "Real part of complex relative permeability of material, which is \\(\\mu_{\\textrm{r}}^{'}\\) in \\(\\mu_r = \\mu_{\\textrm{r}}^{'} - j \\mu_{\\textrm{r}}^{''}\\)."
                     },
                     {
                         "type": [
                             "number",
                             "null"
                         ],
-                        "description": "Imaginary part of complex permeability of material."
+                        "description": "Imaginary part of complex relative permeability of material, which is \\(\\mu_{\\textrm{r}}^{''}\\) in \\(\\mu_{\\textrm{r}} = \\mu_{\\textrm{r}}^{'} - j \\mu_{\\textrm{r}}^{''}\\)."
                     },
                     {
                         "type": [
                             "number",
                             "null"
                         ],
-                        "description": "Real part of complex permittivity of material."
+                        "description": "Real part of complex relative permittivity of material, which is \\(\\epsilon_{\\textrm{r}}^{'}\\) in \\(\\epsilon_{\\textrm{r}} = \\epsilon_{\\textrm{r}}^{'} - j \\epsilon_{\\textrm{r}}^{''}\\)."
                     },
                     {
                         "type": [
                             "number",
                             "null"
                         ],
-                        "description": "Imaginary part of complex permittivity of material."
+                        "description": "Imaginary part of complex relative permittivity of material, which is \\(\\epsilon_{\\textrm{r}}^{''}\\) in \\(\\epsilon_{\\textrm{r}} = \\epsilon_{\\textrm{r}}^{'} - j \\epsilon_{\\textrm{r}}^{''}\\)."
                     }
                 ],
                 "minItems": 7,
diff --git a/schemas/material_optical_schema.json b/schemas/material_optical_schema.json
index c04bc7c8..428fcdcd 100644
--- a/schemas/material_optical_schema.json
+++ b/schemas/material_optical_schema.json
@@ -96,14 +96,14 @@
                             "number",
                             "null"
                         ],
-                        "description": "Real part of index of refraction of material."
+                        "description": "Real part of index of refraction of material, which is \\(n^{'}\\) in \\(n = n^{'} - j \\kappa\\)."
                     },
                     {
                         "type": [
                             "number",
                             "null"
                         ],
-                        "description": "Imaginary part of index of refraction of material."
+                        "description": "Imaginary part of index of refraction of material, which is \\(\\kappa\\) in \\(n = n^{'} - j \\kappa\\)."
                     }
                 ],
                 "minItems": 4,