Pan 4th letter and 44AB

Dear Sir,

1]What fourth letter in pan depicts as fourth letter is ' L'

2] Is it local body? as assessee carrying NGO and even paid tax last year.

3] Turnover of NGO from Contract receipt from Central Govt more than Rs 1 crore , is NGO liable for 44AB audit , if yes then on whose name digital signature of NGO must be taken as e-filling of ITR and Audit ?

Kindly resolve the query at earliest and thanks for viewing.