Issue decoding NAS messages with variant LENGTHTO

Dear Support,

In the context of ETSI TTF project, we are facing issues to decode NAS messages using variants. Here is an example:

  type record NG_MobileIdentity {                              // 24.501 cl. 9.11.3.4
    IEI8_Type            iei                   optional, /* present in case of TLV; omit in case of LV */
    Type6Length_Type     iel,
    BcdDigit_Bit         idDigit1,                // 1st identitity digit
    B1_Type              oddEvenInd,              // Odd/even indicator or Spare
    NAS_IdType           typeOfId,                // Type of identity
    octetstring          otherDigits length (1..infinity) optional  // Other identity digits, could be any length @sic R5-192389, @sic R5w190307 sic@ sic@
  } with {
    variant "FIELDORDER(msb)";
    variant (iel) "LENGTHTO(idDigit1, oddEvenInd, typeOfId, otherDigits)";
  };

The iel field is decoded in reverse order (value shall be '000D'O):

Here is the issue: .iel := '0D00'O with '000D'O

The iel field is declared as:

type octetstring              O2_Type         length(2) with { variant "FIELDLENGTH(2)" };

I tried to use NAS_EPS_Types.ttcn as a model to set my variants but I still facing to the issue.

I have attached a small project file to highlight the issue.

Many thanks for your support,

Best regards,

Yann Garcia
Senior Software Engineer

Microsoft MCAD.net Certified
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titan_5gnas_codec_issue.tbz2