Update README.md

README.md

@@ -93,19 +93,21 @@ Below, an example of data instance.
 The allowed **ner-tags** are: 
   - **O**: An O tag indicates that a token belongs to no chunk.
   - **B-Actor**: This tag indicates the beginning of an *Actor* chunk.
-  - "I-Actor",
-  - "B-Activity",
-  - "I-Activity",
-  - "B-Activity Data",
-  - "I-Activity Data",
-  - "B-Further Specification",
-  - "I-Further Specification",
-  - "B-XOR Gateway",
-  - "I-XOR Gateway",
-  - "B-Condition Specification",
-  - "I-Condition Specification",
-  - "B-AND Gateway",
-  - "I-AND Gateway",
+  - **I-Actor**: This tag indicates that the tag is inside an *Actor*  chunk.
+  - **B-Activity**: This tag indicates the beginning of an *Activity* chunk.
+  - **I-Activity**: This tag indicates that the tag is inside an *Activity* chunk.
+  - **B-Activity Data**: This tag indicates the beginning of an *Activity Data* chunk.
+  - **I-Activity Data**: This tag indicates that the tag is inside an *Activity Data* chunk.
+  - **B-Further Specification**: This tag indicates the beginning of a *Further Specification* chunk.
+  - **I-Further Specification**: This tag indicates that the tag is inside a *Further Specification* chunk.
+  - **B-XOR Gateway**: This tag indicates the beginning of a *XOR Gateway* chunk.
+  - **I-XOR Gateway**: This tag indicates that the tag is inside a *XOR Gateway* chunk.
+  - **B-Condition Specification**: This tag indicates the beginning of a *Condition Specification* chunk.
+  - **I-Condition Specification**: This tag indicates that the tag is inside a *Condition Specification* chunk.
+  - **B-AND Gateway**: This tag indicates the beginning of an *AND Gateway* chunk.
+  - **I-AND Gateway**: This tag indicates that the tag is inside an *AND Gateway* chunk.
+
+To have a complete explanation of each process element tag please refer to the [research paper](https://arxiv.org/abs/2203.04860) and the [annotation guidelines](https://pdi.fbk.eu/pet/annotation-guidelines-for-process-description.pdf).
 
 ### Data Splits