@lahiru_ten I came up with this workflow. I extract the color of the cells of the first column with the help of the Python integration and OpenPyxl and use that to identify the block forming the sub-tables.
Then I create a new column that would assign the “Drawing Number” to all lines - with the identified blocks.
A few things to note if you are new to KNIME:
The Path and the name of the sheet is being captured in Flow Variables to be used later. You can adapt this settings and also use this in Loops.
Column Expression node is used to set the Drawing Number when the right (family of) colours is being found. You could also work with a reference table here matching all Drawing Numbers.
The missing value node uses a special setting of bringing the previous entry to the missings so as to define the blocks of numbers
