CreateSubfield creates a new instance of a field based on the input provided.

NewComposite creates a new instance of the *Composite struct, validates and sets its Spec before returning it.

NewHexValue creates a new Hex field with the given value The value is converted from hex to bytes before packing, so we don't validate that val is a valid hex string here.

Bitmap is a 1-indexed big endian bitmap field.

Composite is a wrapper object designed to hold ISO8583 TLVs, subfields and subelements.

Hex field allows working with hex strings but under the hood it's a binary field.

Spec defines the structure of a field.

TagSpec is used to define the format of field tags (sometimes defined as field IDs).

CompositeWithSubfields is used when composite field is created without calling NewComposite e.g.

Packer is the interface that wraps the Pack method.

Unpacker is the interface that wraps the Unpack method.

Custom type to sort keys in resulting JSON.

PackerFunc is a function type that implements the Packer interface.

UnpackerFunc is a function type that implements the Unpacker interface.