src/libraries/System.Security.Cryptography.Pkcs/src/System/Security/Cryptography/Pkcs/Asn1/IssuerAndSerialNumberAsn.xml

<?xml version="1.0" encoding="utf-8" ?>
<asn:Sequence
  xmlns:asn="http://schemas.dot.net/asnxml/201808/"
  name="IssuerAndSerialNumberAsn"
  namespace="System.Security.Cryptography.Pkcs.Asn1">

  <!--
    https://tools.ietf.org/html/rfc5652#section-10.2.4

    IssuerAndSerialNumber ::= SEQUENCE {
        issuer Name,
        serialNumber CertificateSerialNumber
    }

    CertificateSerialNumber ::= INTEGER
  -->
  <asn:AnyValue name="Issuer" universalTagNumber="16" />
  <asn:Integer name="SerialNumber"  backingType="ReadOnlyMemory" />
</asn:Sequence>