http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5. 
public class org.bouncycastle.asn1.x9.X9FieldID extends org.bouncycastle.asn1.ASN1Encodable implements org.bouncycastle.asn1.x9.X9ObjectIdentifiers
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.bouncycastle.asn1.x9.X9FieldID
  super_class: org.bouncycastle.asn1.ASN1Encodable
{
  private org.bouncycastle.asn1.DERObjectIdentifier id;
    descriptor: Lorg/bouncycastle/asn1/DERObjectIdentifier;
    flags: (0x0002) ACC_PRIVATE

  private org.bouncycastle.asn1.DERObject parameters;
    descriptor: Lorg/bouncycastle/asn1/DERObject;
    flags: (0x0002) ACC_PRIVATE

  public void <init>(java.math.BigInteger);
    descriptor: (Ljava/math/BigInteger;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=2, args_size=2
        start local 0 // org.bouncycastle.asn1.x9.X9FieldID this
        start local 1 // java.math.BigInteger primeP
         0: .line 29
            aload 0 /* this */
            invokespecial org.bouncycastle.asn1.ASN1Encodable.<init>:()V
         1: .line 31
            aload 0 /* this */
            getstatic org.bouncycastle.asn1.x9.X9FieldID.prime_field:Lorg/bouncycastle/asn1/ASN1ObjectIdentifier;
            putfield org.bouncycastle.asn1.x9.X9FieldID.id:Lorg/bouncycastle/asn1/DERObjectIdentifier;
         2: .line 32
            aload 0 /* this */
            new org.bouncycastle.asn1.DERInteger
            dup
            aload 1 /* primeP */
            invokespecial org.bouncycastle.asn1.DERInteger.<init>:(Ljava/math/BigInteger;)V
            putfield org.bouncycastle.asn1.x9.X9FieldID.parameters:Lorg/bouncycastle/asn1/DERObject;
         3: .line 33
            return
        end local 1 // java.math.BigInteger primeP
        end local 0 // org.bouncycastle.asn1.x9.X9FieldID this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0    4     0    this  Lorg/bouncycastle/asn1/x9/X9FieldID;
            0    4     1  primeP  Ljava/math/BigInteger;
    MethodParameters:
        Name  Flags
      primeP  

  public void <init>(int, int, int, int);
    descriptor: (IIII)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=7, args_size=5
        start local 0 // org.bouncycastle.asn1.x9.X9FieldID this
        start local 1 // int m
        start local 2 // int k1
        start local 3 // int k2
        start local 4 // int k3
         0: .line 50
            aload 0 /* this */
            invokespecial org.bouncycastle.asn1.ASN1Encodable.<init>:()V
         1: .line 52
            aload 0 /* this */
            getstatic org.bouncycastle.asn1.x9.X9FieldID.characteristic_two_field:Lorg/bouncycastle/asn1/ASN1ObjectIdentifier;
            putfield org.bouncycastle.asn1.x9.X9FieldID.id:Lorg/bouncycastle/asn1/DERObjectIdentifier;
         2: .line 53
            new org.bouncycastle.asn1.ASN1EncodableVector
            dup
            invokespecial org.bouncycastle.asn1.ASN1EncodableVector.<init>:()V
            astore 5 /* fieldIdParams */
        start local 5 // org.bouncycastle.asn1.ASN1EncodableVector fieldIdParams
         3: .line 54
            aload 5 /* fieldIdParams */
            new org.bouncycastle.asn1.DERInteger
            dup
            iload 1 /* m */
            invokespecial org.bouncycastle.asn1.DERInteger.<init>:(I)V
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
         4: .line 56
            iload 3 /* k2 */
            ifne 8
         5: .line 58
            aload 5 /* fieldIdParams */
            getstatic org.bouncycastle.asn1.x9.X9FieldID.tpBasis:Lorg/bouncycastle/asn1/ASN1ObjectIdentifier;
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
         6: .line 59
            aload 5 /* fieldIdParams */
            new org.bouncycastle.asn1.DERInteger
            dup
            iload 2 /* k1 */
            invokespecial org.bouncycastle.asn1.DERInteger.<init>:(I)V
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
         7: .line 60
            goto 14
         8: .line 63
      StackMap locals: org.bouncycastle.asn1.x9.X9FieldID int int int int org.bouncycastle.asn1.ASN1EncodableVector
      StackMap stack:
            aload 5 /* fieldIdParams */
            getstatic org.bouncycastle.asn1.x9.X9FieldID.ppBasis:Lorg/bouncycastle/asn1/ASN1ObjectIdentifier;
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
         9: .line 64
            new org.bouncycastle.asn1.ASN1EncodableVector
            dup
            invokespecial org.bouncycastle.asn1.ASN1EncodableVector.<init>:()V
            astore 6 /* pentanomialParams */
        start local 6 // org.bouncycastle.asn1.ASN1EncodableVector pentanomialParams
        10: .line 65
            aload 6 /* pentanomialParams */
            new org.bouncycastle.asn1.DERInteger
            dup
            iload 2 /* k1 */
            invokespecial org.bouncycastle.asn1.DERInteger.<init>:(I)V
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
        11: .line 66
            aload 6 /* pentanomialParams */
            new org.bouncycastle.asn1.DERInteger
            dup
            iload 3 /* k2 */
            invokespecial org.bouncycastle.asn1.DERInteger.<init>:(I)V
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
        12: .line 67
            aload 6 /* pentanomialParams */
            new org.bouncycastle.asn1.DERInteger
            dup
            iload 4 /* k3 */
            invokespecial org.bouncycastle.asn1.DERInteger.<init>:(I)V
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
        13: .line 68
            aload 5 /* fieldIdParams */
            new org.bouncycastle.asn1.DERSequence
            dup
            aload 6 /* pentanomialParams */
            invokespecial org.bouncycastle.asn1.DERSequence.<init>:(Lorg/bouncycastle/asn1/ASN1EncodableVector;)V
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
        end local 6 // org.bouncycastle.asn1.ASN1EncodableVector pentanomialParams
        14: .line 71
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            new org.bouncycastle.asn1.DERSequence
            dup
            aload 5 /* fieldIdParams */
            invokespecial org.bouncycastle.asn1.DERSequence.<init>:(Lorg/bouncycastle/asn1/ASN1EncodableVector;)V
            putfield org.bouncycastle.asn1.x9.X9FieldID.parameters:Lorg/bouncycastle/asn1/DERObject;
        15: .line 72
            return
        end local 5 // org.bouncycastle.asn1.ASN1EncodableVector fieldIdParams
        end local 4 // int k3
        end local 3 // int k2
        end local 2 // int k1
        end local 1 // int m
        end local 0 // org.bouncycastle.asn1.x9.X9FieldID this
      LocalVariableTable:
        Start  End  Slot               Name  Signature
            0   16     0               this  Lorg/bouncycastle/asn1/x9/X9FieldID;
            0   16     1                  m  I
            0   16     2                 k1  I
            0   16     3                 k2  I
            0   16     4                 k3  I
            3   16     5      fieldIdParams  Lorg/bouncycastle/asn1/ASN1EncodableVector;
           10   14     6  pentanomialParams  Lorg/bouncycastle/asn1/ASN1EncodableVector;
    MethodParameters:
      Name  Flags
      m     
      k1    
      k2    
      k3    

  public void <init>(org.bouncycastle.asn1.ASN1Sequence);
    descriptor: (Lorg/bouncycastle/asn1/ASN1Sequence;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=2
        start local 0 // org.bouncycastle.asn1.x9.X9FieldID this
        start local 1 // org.bouncycastle.asn1.ASN1Sequence seq
         0: .line 74
            aload 0 /* this */
            invokespecial org.bouncycastle.asn1.ASN1Encodable.<init>:()V
         1: .line 77
            aload 0 /* this */
            aload 1 /* seq */
            iconst_0
            invokevirtual org.bouncycastle.asn1.ASN1Sequence.getObjectAt:(I)Lorg/bouncycastle/asn1/DEREncodable;
            checkcast org.bouncycastle.asn1.DERObjectIdentifier
            putfield org.bouncycastle.asn1.x9.X9FieldID.id:Lorg/bouncycastle/asn1/DERObjectIdentifier;
         2: .line 78
            aload 0 /* this */
            aload 1 /* seq */
            iconst_1
            invokevirtual org.bouncycastle.asn1.ASN1Sequence.getObjectAt:(I)Lorg/bouncycastle/asn1/DEREncodable;
            checkcast org.bouncycastle.asn1.DERObject
            putfield org.bouncycastle.asn1.x9.X9FieldID.parameters:Lorg/bouncycastle/asn1/DERObject;
         3: .line 79
            return
        end local 1 // org.bouncycastle.asn1.ASN1Sequence seq
        end local 0 // org.bouncycastle.asn1.x9.X9FieldID this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    4     0  this  Lorg/bouncycastle/asn1/x9/X9FieldID;
            0    4     1   seq  Lorg/bouncycastle/asn1/ASN1Sequence;
    MethodParameters:
      Name  Flags
      seq   

  public org.bouncycastle.asn1.DERObjectIdentifier getIdentifier();
    descriptor: ()Lorg/bouncycastle/asn1/DERObjectIdentifier;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.bouncycastle.asn1.x9.X9FieldID this
         0: .line 83
            aload 0 /* this */
            getfield org.bouncycastle.asn1.x9.X9FieldID.id:Lorg/bouncycastle/asn1/DERObjectIdentifier;
            areturn
        end local 0 // org.bouncycastle.asn1.x9.X9FieldID this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/bouncycastle/asn1/x9/X9FieldID;

  public org.bouncycastle.asn1.DERObject getParameters();
    descriptor: ()Lorg/bouncycastle/asn1/DERObject;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.bouncycastle.asn1.x9.X9FieldID this
         0: .line 88
            aload 0 /* this */
            getfield org.bouncycastle.asn1.x9.X9FieldID.parameters:Lorg/bouncycastle/asn1/DERObject;
            areturn
        end local 0 // org.bouncycastle.asn1.x9.X9FieldID this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/bouncycastle/asn1/x9/X9FieldID;

  public org.bouncycastle.asn1.DERObject toASN1Object();
    descriptor: ()Lorg/bouncycastle/asn1/DERObject;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=1
        start local 0 // org.bouncycastle.asn1.x9.X9FieldID this
         0: .line 102
            new org.bouncycastle.asn1.ASN1EncodableVector
            dup
            invokespecial org.bouncycastle.asn1.ASN1EncodableVector.<init>:()V
            astore 1 /* v */
        start local 1 // org.bouncycastle.asn1.ASN1EncodableVector v
         1: .line 104
            aload 1 /* v */
            aload 0 /* this */
            getfield org.bouncycastle.asn1.x9.X9FieldID.id:Lorg/bouncycastle/asn1/DERObjectIdentifier;
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
         2: .line 105
            aload 1 /* v */
            aload 0 /* this */
            getfield org.bouncycastle.asn1.x9.X9FieldID.parameters:Lorg/bouncycastle/asn1/DERObject;
            invokevirtual org.bouncycastle.asn1.ASN1EncodableVector.add:(Lorg/bouncycastle/asn1/DEREncodable;)V
         3: .line 107
            new org.bouncycastle.asn1.DERSequence
            dup
            aload 1 /* v */
            invokespecial org.bouncycastle.asn1.DERSequence.<init>:(Lorg/bouncycastle/asn1/ASN1EncodableVector;)V
            areturn
        end local 1 // org.bouncycastle.asn1.ASN1EncodableVector v
        end local 0 // org.bouncycastle.asn1.x9.X9FieldID this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    4     0  this  Lorg/bouncycastle/asn1/x9/X9FieldID;
            1    4     1     v  Lorg/bouncycastle/asn1/ASN1EncodableVector;
}
SourceFile: "X9FieldID.java"