YAML Ain©t Markup Language (YAML™) Version 1.1 Working Draft 2004-12-28 Oren Ben-Kiki <[email protected]> Clark Evans <[email protected]> Brian Ingerson <[email protected]> XSL·FO RenderX YAML Ain©t Markup Language (YAML™) Version 1.1 Working Draft 2004-12-28 by Oren Ben-Kiki, Clark Evans, and Brian Ingerson Copyright © 2001-2004 Oren Ben-Kiki, Clark Evans, Brian Ingerson Status of this Document This specification is a draft reflecting consensus reached by members of the yaml-core mailing list [http://lists.sourceforge.net/lists/listinfo/yaml-core]. Any questions regarding this draft should be raised on this list. We expect all further changes will be strictly limited to wording corrections and fixing production bugs. We wish to thank implementers who have tirelessly tracked earlier versions of this specification, and our fabulous user community whose feedback has both validated and clarified our direction. Abstract YAML™ (rhymes with ªcamelº) is a human-friendly, cross language, Unicode based data serialization language designed around the common native data structures of agile programming languages. It is broadly useful for programming needs ranging from configuration files to Internet messaging to object persistence to data auditing. Together with the Unicode standard for characters [http://www.unicode.org/], this specification provides all the information necessary to understand YAML Version 1.1 and to creating programs that process YAML information. This document may be freely copied provided it is not modified. XSL·FO RenderX Table of Contents 1. Introduction ........................................................................................................................................ 1 1.1. Goals .......................................................................................................................................... 1 1.2. Prior Art ...................................................................................................................................... 1 1.3. Relation to XML ........................................................................................................................... 2 1.4. Terminology ................................................................................................................................. 3 2. Preview .............................................................................................................................................. 4 2.1. Collections ................................................................................................................................... 4 2.2. Structures ..................................................................................................................................... 5 2.3. Scalars ......................................................................................................................................... 6 2.4. Tags ............................................................................................................................................ 7 2.5. Full Length Example ...................................................................................................................... 9 3. Processing YAML Information ............................................................................................................. 10 3.1. Processes .................................................................................................................................... 10 3.1.1. Represent ............................................................................................................................. 10 3.1.2. Serialize .............................................................................................................................. 11 3.1.3. Present ................................................................................................................................ 11 3.1.4. Parse ................................................................................................................................... 11 3.1.5. Compose .............................................................................................................................. 11 3.1.6. Construct ............................................................................................................................. 11 3.2. Information Models ...................................................................................................................... 11 3.2.1. Representation Graph ............................................................................................................. 12 3.2.1.1. Nodes ........................................................................................................................... 13 3.2.1.2. Tags ............................................................................................................................. 13 3.2.1.3. Nodes Comparison .......................................................................................................... 14 3.2.2. Serialization Tree .................................................................................................................. 14 3.2.2.1. Keys Order .................................................................................................................... 15 3.2.2.2. Anchors and Aliases ........................................................................................................ 15 3.2.3. Presentation Stream ............................................................................................................... 15 3.2.3.1. Node Styles ................................................................................................................... 16 3.2.3.2. Scalar Formats ................................................................................................................ 17 3.2.3.3. Comments ..................................................................................................................... 17 3.2.3.4. Directives ...................................................................................................................... 17 3.3. Loading Failure Points .................................................................................................................. 17 3.3.1. Well-Formed and Identified ..................................................................................................... 18 3.3.2. Resolved .............................................................................................................................. 18 3.3.3. Recognized and Valid ............................................................................................................ 19 3.3.4. Available ............................................................................................................................. 19 4. Syntax .............................................................................................................................................. 20 4.1. Characters .................................................................................................................................. 20 4.1.1. Character Set ........................................................................................................................ 20 4.1.2. Character Encoding ................................................................................................................ 21 4.1.3. Indicator Characters ............................................................................................................... 21 4.1.4. Line Break Characters ............................................................................................................ 25 4.1.5. Miscellaneous Characters ........................................................................................................ 26 4.1.6. Escape Sequences .................................................................................................................. 28 4.2. Syntax Primitives ......................................................................................................................... 30 4.2.1. Production Parameters ............................................................................................................ 30 4.2.2. Indentation Spaces ................................................................................................................. 31 4.2.3. Comments ............................................................................................................................ 32 4.2.4. Separation Spaces .................................................................................................................. 33 4.2.5. Ignored Line Prefix ................................................................................................................ 34 iii XSL·FO RenderX YAML Ain©t Markup Lan- guage (YAML™) Version 1.1 4.2.6. Line Folding ......................................................................................................................... 35 4.3. YAML Character Stream ............................................................................................................... 36 4.3.1. Directives ............................................................................................................................ 37 4.3.1.1. YAML Directive ............................................................................................................