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Julian D. A. Wiseman
Contents: Publication history; Introduction; The Code
Publication history: only at www.jdawiseman.com/papers/trivia/isin.html. Usual disclaimer and copyright terms apply.
To facilitate settlement and hence trading of securities, each security has a unique identifying code. There are several types of identifying code, the one that is used internationally being the ISIN, or International Securities Identifying Number. Every security in almost every country has an ISIN (possibly excepting Colombia, whose government bonds—uniquely—appear to lack an ISIN). The structure of an ISIN is defined in ISO 6166, and the algorithm is described by Wikipedia. Defined below is an Excel VBA function LastDigitISIN(ElevenChars As String) As String that returns the last digit of an ISIN given the first eleven.
UK securities also have a SEDOL number, also defined in Wikipedia. The function LastDigitSEDOL(SixChars As String) As String returns the last digit given the first ≤6 characters. If the input is shorter than six characters it is left-padded with zeroes.
ISINs of UK securities are typically made by prefixing the SEDOL with “GB00” (and perhaps with “IE00” for Irish securities) and suffixing with the ISIN checksum. ISINfromSEDOL6(CountryCode As String, SixChars As String) As String computes the ISIN given the first six characters of the SEDOL.
The code was written for Microsoft Excel, though should work in Access if prefixed with a line “Attribute VB_Name = "modIsin"”. The original was © Julian D. A. Wiseman 2006 and 2007, though in 2009 was modified by Patrick Honorez of www.idevlop.com, primarily to replace Excel-specific code with more general code and to add the function IsIsin, and then further modified by Julian D. A. Wiseman. It may be distributed under the terms of the GNU General Public License.
Occasionally kCountries3166 will need to be extended.
Option Explicit Const kCountries3166 = "AD;AE;AF;AG;AI;AL;AM;AN;AO;AQ;AR;AS;AT;AU;AW;AX;AZ;BA;BB;BD;BE;BF;BG;BH;BI;BJ;BL;BM;BN;BO;BR;BS;BT;BV;BW;BY;BZ;CA;CC;CD;CF;CG;CH;CI;CK;CL;CM;CN;CO;CR;CU;CV;CX;CY;CZ;DE;DJ;DK;DM;DO;DZ;EC;EE;EG;EH;ER;ES;ET;FI;FJ;FK;FM;FO;FR;GA;GB;GD;GE;GF;GG;GH;GI;GL;GM;GN;GP;GQ;GR;GS;GT;GU;GW;GY;HK;HM;HN;HR;HT;HU;ID;IE;IL;IM;IN;IO;IQ;IR;IS;IT;JE;JM;JO;JP;KE;KG;KH;KI;KM;KN;KP;KR;KW;KY;KZ;LA;LB;LC;LI;LK;LR;LS;LT;LU;LV;LY;MA;MC;MD;ME;MF;MG;MH;MK;ML;MM;MN;MO;MP;MQ;MR;MS;MT;MU;MV;MW;MX;MY;MZ;NA;NC;NE;NF;NG;NI;NL;NO;NP;NR;NU;NZ;OM;PA;PE;PF;PG;PH;PK;PL;PM;PN;PR;PS;PT;PW;PY;QA;RE;RO;RS;RU;RW;SA;SB;SC;SD;SE;SG;SH;SI;SJ;SK;SL;SM;SN;SO;SR;ST;SV;SY;SZ;TC;TD;TF;TG;TH;TJ;TK;TL;TM;TN;TO;TR;TT;TV;TW;TZ;UA;UG;UM;US;UY;UZ;VA;VC;VE;VG;VI;VN;VU;WF;WS;XS;YE;YT;ZA;ZM;ZW" ' Given the first eleven characters of an ISIN, this calculates the twelfth character, the checksum. ' © Julian D. A. Wiseman 2006 to 2009; parts, including some de-Excel-isation, by and © Patrick Honorez of www.idevlop.com. ' Believed correct. If it doesn’t always work then tough—it is free. ' Latest version available via http://www.jdawiseman.com/papers/trivia/isin.html Public Function IsIsin(ByVal strIsin As Variant, Optional strCountries As String = kCountries3166) As Boolean ' Added by Patrick Honorez of www.idevlop.com ' Returns True if string looks like a valid ISIN, False otherwise ' Parameters: strIsin : ISIN to check, as a string (Null accepted) ' strCountries: optional list of countries. If not provided, default list will be used. ' if provided with empty string, this check will be bypassed ' Note: some checks are redundant, but are there for speed. Const kIsinLike = "[A-Z][A-Z]?????????[0-9]" Dim strCheck As String If IsNull(strIsin) Then Exit Function ' Null values If Len(strIsin) <> 12 Then Exit Function ' Will return False If Not strIsin Like kIsinLike Then Exit Function ' Will return False If Len(strCountries) > 0 Then ' Test country code ? If InStr(1, strCountries, Left(strIsin, 2)) = 0 Then Exit Function End If ' Len(strCountries) > 0 strCheck = LastDigitISIN(Left(strIsin, 11)) ' Check digit If Not strCheck Like "[0-9]" Then Exit Function ' LastDigitIsin returned an error If Right(strIsin, 1) = strCheck Then IsIsin = True End Function ' IsIsin Public Function LastDigitISIN(ElevenChars As String) As String Dim i As Integer, CheckSumDigits As String, TotalScore As Integer, Char As String If Len(ElevenChars) <> 11 Then LastDigitISIN = "L" ' Length error Exit Function End If ' Len(ElevenChars) <> 11 CheckSumDigits = "" For i = 1 To 11 Char = UCase(Mid(ElevenChars, i, 1)) If Char >= "0" And Char <= "9" Then CheckSumDigits = CheckSumDigits & Char ElseIf Char >= "A" And Char <= "Z" Then CheckSumDigits = CheckSumDigits & (10 + Asc(Char) - Asc("A")) Else LastDigitISIN = "C" ' Character error Exit Function End If Next i TotalScore = 0 For i = 1 To Len(CheckSumDigits) If (i + Len(CheckSumDigits)) Mod 2 Then TotalScore = TotalScore + Val(Mid(CheckSumDigits, i, 1)) Else TotalScore = TotalScore + Choose(1 + Val(Mid(CheckSumDigits, i, 1)), 0, 2, 4, 6, 8, 1, 3, 5, 7, 9) End If ' 0 = (i + Len(CheckSumDigits)) Mod 2 Next i LastDigitISIN = Format((130 - TotalScore) Mod 10, "0") End Function ' LastDigitISIN(ElevenChars As String) As String Public Function LastDigitSEDOL(SixChars As String) As String ' SixChars front padded with zeroes Dim i As Integer, Char As String, Multiplier As Integer, TotalScore As Integer If Len(SixChars) > 6 Then LastDigitSEDOL = "L" ' Length error Exit Function End If ' Len(SixChars) > 6 For i = 1 To Len(SixChars) Multiplier = Choose(i + 6 - Len(SixChars), 1, 3, 1, 7, 3, 9) Char = UCase(Mid(SixChars, i, 1)) If Char >= "0" And Char <= "9" Then TotalScore = TotalScore + Char * Multiplier ElseIf Char >= "A" And Char <= "Z" Then TotalScore = TotalScore + (10 + Asc(Char) - Asc("A")) * Multiplier Else LastDigitSEDOL = "C" ' Character error Exit Function End If Next i LastDigitSEDOL = (870 - TotalScore) Mod 10 End Function ' LastDigitSEDOL(SixChars As String) As String Public Function ISINfromSEDOL6(CountryCode As String, SixChars As String) As String ISINfromSEDOL6 = CountryCode & "00" _ & String("0", 6 - Len(SixChars)) & SixChars & LastDigitSEDOL(SixChars) ISINfromSEDOL6 = ISINfromSEDOL6 & LastDigitISIN(ISINfromSEDOL6) End Function ' ISINfromSEDOL6(CountryCode3166 As String, SixChars As String) As String
Julian D. A. Wiseman
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