[BlindMath] Examples 10.7.1 in the UEB Rulebook 2nd ed: Why not use the st sign in the word "Youngstown"?

[Saaqib Mahmuud]

 Hi mates? Hope you're doing well.

I have a few queries regarding the UEB Rulebook, 2nd edition, 2013.


In 10.7.1 examples, 
1. why has the strong groupsign for "st" not been used in the word "Youngstown". What is preventing the use of this contraction here? 2. why not use the initial-letter contraction dot 5 d in the words "Dayan", "Sanday", or "today"? What is the caveat?
3. why has the contraction dot 5 l not been used in the word "chlordane", whereas this very contraction has been used in the word "lordosis"?
4. why has the dot 5 p contraction not been used in the word "Parthenon", where this same contraction has been used in the word "partake" and "parterre"? 

In the light of the above, how can one justify the use of the dots 45 w contraction in the word "sword"?

Regards.

Saaqib