It's wagon numbering system ..

New wagon numbering system has been adopted in Indian Railways in 2003. Wagons are given with 11 digit numbers making it easy for identification and digitalizing wagon information.
1)First two digits will indicate Type or Wagon. Eg. BOXN, BCN, BCNA etc. Different wagon types are given numbers from 10 to 99.
2)Next...
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two digits will indicate Owning Railway. Eg. SR -06, CR-01, 16 Zones are given numbers from 01 to 16 and 25 for CONCOR, 26 for Private owned wagons and 24 for wagons owned by defence.
3)Next two digits will indicate Year or Manufacture. eg.13 for 2013.
4)Next four digits will indicate Individual Wagon Number (0001 to 1000 for Departmental and 1001 to 9999 for Commercial purpose).
5)Last digit will be a Check digit.!!
.
Here is the details for 221010 70355
22 - Code allotted for BOXNHL.
10 - Owning By East Central Railway.
10 - Year of manufacture.
7035 - Individual wagon No.
5 - Check digit..

Means
22-Boxnhl
10-ECR (zone)
10-2010
7035 -number
But...
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what is check digit 🤔🤔

CHECK DIGIT — Method of calculation
The 'Check Digit' for each wagon is calculated using a six-step algorithm based on ten
digit wagon number arrived at as indicated below.
Step — 1 Starting from the left, add , all the Characters in the even position.
S1=C2+C4+C6+C8+C10...
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Step — 2 Multiply the sum by 3 to get 3S1
Step — 3 Starting from the left, add all the Characters in the odd position.
S2=C1+C3+C5+C7+C9
Step — 4 Add the sum of step 2 to the sum of step 3 to get S4=3S1+S2
Step — 5 Round this total up to the next multiple of 10.
Step — 6 The check digit is the number required to be added to round up to the next
multiple of 10..!!