Working Draft 2005-01-18 Oren Ben-Kiki oren@ben-kiki.org Clark Evans cce+yaml@clarkevans.com Brian Ingerson ingy@ttul.org 2001-2005 Oren Ben-Kiki,  Clark Evans,  Brian Ingerson This document may be freely copied provided it is not modified. This specification is a draft reflecting consensus reached by members of the yaml-core mailing list. Any questions regarding this draft should be raised on this list.

URI: tag:yaml.org,2002:yaml Shorthand: !!yaml Kind: Scalar. Canonical: N/A (single format). Regexp: !|&|\* Definition: Keys for encoding YAML in YAML. YAML encoding keys are used to denote YAML structure information. The in-memory representation of these keys must be different from any value in any other type family. Specifically, these in-memory values must not be implemented as strings. Normally, the encoding keys should not be used in serialized YAML documents; the encoded YAML node is serialized instead. Encoding is useful when a YAML processor encounters a valid YAML value of an unknown tag. For a schema-specific application, this is not different from encountering any other valid YAML document that does not satisfy the schema. Such an application may safely use a processor that rejects any value of any unknown tag, or discards the tag property with an appropriate warning and parses the value as if the property was not present. For a schema-independent application (for example, a hypothetical YAML pretty print application), this is not an option. Processors used by such applications should encode the value instead. This may be done by wrapping the value in a mapping containing encoding keys. The ! key denotes the unsupported tag. In some cases it may be necessary to encode anchors and alias nodes as well. The & and * keys are used for this purpose. Encoding should be reversed on output, allowing the schema-independent application to safely round-trip any valid YAML document. In-memory, the encoded data may be accessed and manipulated in a standard way using the three basic data types (mapping, sequence and scalar), allowing limited processing to be applied to arbitrary YAML data. # The following node should NOT be serialized this way. encoded YAML node : !!yaml '!' : '!type' !!yaml '&' : 12 !!value = : value # The proper way to serialize the above node is as follows: node : !type &12 value