Technical Specification - RSID Registry

1. Overview

RSID (Reference Security Identifier) provides standardized 7-character alphanumeric codes for securities. Designed for custodian platforms with fixed field-length constraints, particularly for U.S., Canadian, and other securities requiring operational identifiers.

2. Structure

Format: 7 characters total (6 identifier + 1 check digit)

Position	Content	Description
1	R	Fixed prefix (all RSID codes begin with R)
2-6	Alphanumeric	Unique identifier sequence
7	0-9	Check digit for validation

Example: RBCDFG3 → R (prefix) + BCDFG (identifier) + 3 (check digit)

3. Character Set

Allowed: B, C, D, F, G, H, J, K, L, M, N, P, Q, R, S, T, V, W, X, Y, Z, 0-9

Excluded: Vowels (A, E, I, O, U) to minimize visual confusion and transcription errors

Position 1: Always "R" (fixed prefix for immediate identification)

Position 7: Always numeric (0-9) as the calculated check digit

4. Check Digit Algorithm

RSID uses a weighted modulus-10 algorithm with a unique weight pattern for operational validation.

4.1 Character-to-Number Conversion

Character Type	Conversion Rule	Examples
Letters (A-Z)	A=10, B=11, C=12, ... Z=35	R=27, B=11, G=16
Digits (0-9)	Face value	0=0, 5=5, 9=9

4.2 Weight Pattern

RSID uses unique weights: [1, 4, 2, 9, 5, 8] for positions 1-6

Position	Weight	Applied To
1	1	R (prefix)
2	4	1st identifier character
3	2	2nd identifier character
4	9	3rd identifier character
5	5	4th identifier character
6	8	5th identifier character

4.3 Calculation Steps

Convert each character in positions 1-6 to numeric value (A=10...Z=35, 0=0...9=9)
Multiply each value by its position weight [1, 4, 2, 9, 5, 8]
Sum all weighted values
Calculate: Check Digit = (10 - (Sum mod 10)) mod 10
Append check digit as position 7

4.4 Worked Example 1: RBCDFG

Code to validate: RBCDFG?
Step 1 - Convert to numbers:
R=27, B=11, C=12, D=13, F=15, G=16
Step 2 - Apply weights [1,4,2,9,5,8]:
R: 27 × 1 = 27
B: 11 × 4 = 44
C: 12 × 2 = 24
D: 13 × 9 = 117
F: 15 × 5 = 75
G: 16 × 8 = 128
Step 3 - Sum: 27+44+24+117+75+128 = 415
Step 4 - Calculate check digit:
(10 - (415 mod 10)) mod 10
= (10 - 5) mod 10
= 5 mod 10
= 5
Final code: RBCDFG5

4.5 Worked Example 2: RHJKLM

H=17, J=19, K=20, L=21, M=22
R: 27×1=27, H: 17×4=68, J: 19×2=38, K: 20×9=180, L: 21×5=105, M: 22×8=176
Sum = 594
Check = (10 - (594 mod 10)) mod 10 = (10-4) mod 10 = 6
Final code: RHJKLM6

4.6 Worked Example 3: RZ0123

Z=35, 0=0, 1=1, 2=2, 3=3
R: 27×1=27, Z: 35×4=140, 0: 0×2=0, 1: 1×9=9, 2: 2×5=10, 3: 3×8=24
Sum = 210
Check = (10 - (210 mod 10)) mod 10 = (10-0) mod 10 = 0
Final code: RZ01230

4.7 Validation Procedure (for Operations)

To verify any RSID code:

Extract positions 1-6
Calculate check digit using algorithm above
Compare calculated vs. actual (position 7)
If match → Valid code ✓
If mismatch → Flag for review ✗

Use case: Operations teams can validate codes at point of entry, before settlement, or during reconciliation to catch transcription errors.

4.8 Excel Formula

For cell B2 containing 5-character identifier (e.g., "BCDFG"):


                    =MOD(10-MOD(

                    (CODE("R")-55)*1 + 

                    (IF(ISNUMBER(VALUE(MID(B2,1,1))),VALUE(MID(B2,1,1)),(CODE(MID(B2,1,1))-55)))*4 + 

                    (IF(ISNUMBER(VALUE(MID(B2,2,1))),VALUE(MID(B2,2,1)),(CODE(MID(B2,2,1))-55)))*2 + 

                    (IF(ISNUMBER(VALUE(MID(B2,3,1))),VALUE(MID(B2,3,1)),(CODE(MID(B2,3,1))-55)))*9 + 

                    (IF(ISNUMBER(VALUE(MID(B2,4,1))),VALUE(MID(B2,4,1)),(CODE(MID(B2,4,1))-55)))*5 + 

                    (IF(ISNUMBER(VALUE(MID(B2,5,1))),VALUE(MID(B2,5,1)),(CODE(MID(B2,5,1))-55)))*8,

                    10),10)

Download: Excel generator with formulas available on Request Access page

5. Implementation Guidelines

5.1 System Integration

Field Type: CHAR(7) or VARCHAR(7)
Storage: Store as text to preserve leading zeros
Validation: Implement check digit validation at data entry points
Indexing: Recommended for position reference and settlement matching
No Modifications: Codes remain stable through corporate actions

5.2 Operational Procedures

Manual Entry: Use check digit validation to catch transcription errors immediately
Data Import: Validate all RSIDs upon file import or API ingestion
Reconciliation: Use RSID as primary key for non-traditional identifier securities
Exception Handling: Flag validation failures for operations review
Audit Trail: Log all validation failures for compliance purposes

6. Scope & Coverage

Covers: U.S., Canadian, and other securities requiring 7-character operational identifiers

Asset Classes: Equities, fixed income, ETFs, money market instruments, structured products

Use Case: Internal custody operations, settlement, reconciliation, corporate actions

Non-Intelligent: No embedded meaning; codes remain stable through corporate events

7. Legal & Compliance

Intellectual Property: RSID algorithm, codes, and methodology are proprietary to RSID Registry

Independent System: RSID employs unique technical implementations distinct from other identifier systems

Usage: Internal operations permitted free; redistribution requires license

See: Terms & Conditions for complete usage terms

8. Support & Updates

Technical Questions: [email protected]

Registry Updates: Users responsible for obtaining current registry versions

Security Requests: Request additions via Contact page