dsPIC33EV CodeGuard doubt

Hello everyone, 
I think that the document about CodeGuard that you can find here
https://ww1.microchip.com/downloads/en/DeviceDoc/70005182a.pdf
about the dsPIC33 family is not always 100% clear. 
At page 9, there's the detailed description of the segments access rules.
In particular, at page 9 table 4-2 describes BS and GS access rules. 
However the first row of the table consider the Segment Security Level. 
Here's my question: Segment Security Level of the BS or of the GS ?

Let's image I set BS security to HIGH and GS security to NONE. 
Which column do I have to look in the table ?

It looks like they have merged the rules for BS and GS into one table, 
but doing that way makes rules not clear ?
How to really read that table ? 
 

Thank you JPortici for your answer.
I think the following table resumes the table 4-2 in a much more terse and understandable way. Could you check if the table looks correct ?
Target is the memory segment which we try to read/write/erase.
The table states the highest security level that makes the operation possible. 
E.g. is the highest security level is 2 (standard), then the operation is possible only 
with None and Standard, but not with High.
Anyone can feel free to comment, correct, ecc...

GS security level

1: None
2: Standard
3: High

 CODE EXECUTES FROM

 BS GS

 BS 3 1
TARGET 
 GS 2 3
 
Write and Erase are never allowed if the corresponding write protection is ON. 

deleted

More development and some example code. 
I guess that everyone which is active in developing a Bootloader is interested in this 3d.
Again, please read the attached doc file.

Now you will excuse me, but it's Sunday morning and banging my head on some obscure uCHIP table is not the best...