tank marking identification

[krawlings]

I am just a little confused on the marking to tank I just got.I have a LP100 steel tank I would like to get some clerification of the tank markings
(1st ling) DOT 3AA2400
(2nd line) 303500
(3rd ling) SRP
(4TH LINE) 1C72+PST
I KNOW THE 3AA 2400 = STELL 2400psi and next line is sierial #
SRP do not know . last line 1c72 = date of 1st hydo the + not sure and the PST is that the MAKER

 

[Brewone0to]

The + means that during that hydro test it qualified for a 10% overfill rating.
2400+240=2640psi this fill pressure at the tanks volume will produce
the rated cu ft of gas contained in the cylinder.

To maintain + fill status, it must have passed aproval at each hydro-test.
If it passes, it will also have a + symbol with the current hydro stamping.