Update README.md

README.md

@@ -32,6 +32,18 @@ This dataset is a conversion of the original [PubTabNet](https://developer.ibm.c
 * rows: grid row length.
 * image: PIL image
 
+### OTSL Vocabulary:
+
+**OTSL**: new reduced table structure token format
+More information on the OTSL table structure format and its concepts can be read from our paper.
+Format of this dataset extends work presented in a paper, and introduces slight modifications:
+
+* "fcel" - cell that has content in it
+* "ecel" - cell that is empty
+* "lcel" - left-looking cell (to handle horizontally merged cells)
+* "ucel" - up-looking cell (to handle vertically merged cells)
+* "xcel" - 2d span cells, in this dataset - covers entire area of a merged cell
+* "nl" - new line token
 
 ### Data Splits