Welcome to the MEI Guidelines. They provide documentation for the Music Encoding
Initiative's framework for describing music notation documents. This includes both
technical specification of the XML-based implementation of MEI and an explanatory
description of its concepts.
The MEI Guidelines are intended to serve as a reference tool for music encoders.
Through the use of natural-language definitions and examples, this documentation
assists users of MEI in achieving effective and consistent markup. Despite
translating XML and RNG terminology and concepts into more accessible language, it
still a technical one that presupposes a minimal understanding of XML and music
notation. Novice encoders may want to start their MEI experience by doing an introductory
tutorial first. These Guidelines will provide recommendations and arguments
for encoding different types of music notation for a variety of purposes. While the
specification of the framework is complete, the description is not necessarily
complete. MEI is used in various contexts, and not every use-case may be fully
reflected in these Guidelines. However, MEI is a community effort, so feedback and
suggestions for improvement are highly welcome. Several starting points to get in
touch with the MEI community can be found on the MEI
These Guidelines make use of real-world examples to illustrate appropriate encoding
concepts. We consider the use of such images as fair use. Contributors to these
Guidelines are requested to given proper reference to the libraries holding the
material used here. They're also asked to be aware of potential copyright
infringements and avoid respective material, or replace it with hand-drawn, made-up
examples. If you find material that possibly offends copyright, please get in touch with us, and we will
take it down.
1.1About these Guidelines
1.1.1MEI Design Principles
This section of the Guidelines defines principles and criteria for designing,
developing, and maintaining an XML-based encoding scheme for music notation
22.214.171.124Definitions and Parameters
A music notation document is one that contains music notation; that is, any
one of a number of "visual analogues of musical sound, either as a record of
sound heard or imagined, or as a set of visual instructions for performers."
(Ian D. Bent, et al. "Notation." Grove Music Online. Oxford Music Online. 25
May 2010. http://www.oxfordmusiconline.com/subscriber/article/grove/music/20114.)
However, MEI's understanding is more inclusive than this restrictive
definition, i.e. Braille certainly qualifies as music notation
The encoding scheme permits both the creation of new music notation
documents and the conversion of existing ones from print and other
electronic formats. However, conversion of existing documents may require
revisions in content or rearrangement of information.
MEI may be used to encode both primary sources of music notation, such as an
autograph or published score, and secondary sources, such as a scholarly
edition based on one or more primary sources. The format encompasses both
use cases, and the encoder must choose the elements and attributes most
appropriate in each case. These Guidelines aim to provide guidance on that
As an encoded representation of one or more music notation documents, an MEI
file may be employed as a surrogate for the original materials.
Although the encoding scheme does not define or prescribe intellectual
content for music notation documents, it does define content designation and
is intended to be used with available data content standards. MEI identifies
the essential data elements within music notation documents and establishes
codes and conventions necessary for capturing and distinguishing information
within those elements for future action or manipulation. While there are a
few elements that ought to appear in any MEI document, various intellectual,
technical, and economic factors influence the level of detail of analysis
and encoding actually undertaken. Taking this into consideration, the
encoding scheme is designed with a minimum of required elements and allows
for progressively more detailed levels of description as desired.
The encoding scheme preserves and enhances the current functionality of
existing music notation documents. It permits identification of document
structures and content that support description, navigation, analysis, and
online and print presentation.
The encoding scheme is intended to facilitate interchange between notational
tools. It aims to assist in the creation of more effective and consistent
encoding, encourage the creation of cooperatively-created and widely
available databases of music notation documents, and permit the reuse of
encoded data for multiple output purposes. It will also ensure that
machine-readable music notation documents will outlive changing hardware and
software environments because they are based on a platform-independent
The encoding scheme is based on eXtensible Markup Language (XML), a
text-based format for representing structured information. It is expressed
as a One Document Does-it-all (ODD) document. For more information on ODD,
please refer to 1.2.5 Customizing MEI, existing notation encoding schemes,
etc. have been consulted and employed as appropriate. For example, the data
model includes a header that is comparable to the TEI header, and TEI and
EAD naming conventions and tag structures have been used whenever feasible.
However, while some feature names are similar, or even the same, it is
important to recognize that MEI and TEI have different semantic scope.
Obviously, a note element in MEI does not carry the same meaning as the
element of the same name in TEI. Perhaps less obviously, a phrase in music
notation is unrelated to a textual phrase.
With respect to metadata, MEI recognizes the close relationship between the
metadata content found in the MEI header and that of catalog records,
authority records, and finding aids. Therefore MEI provides ways of
indicating in the encoding the corresponding fields of other metadata
To ensure broad international and multi-repertoire application of MEI,
existing musical terminology was used in building the data model where
practical. When appropriate, a more neutral terminology was used to
facilitate sharing of concepts and thus stressing the commonalities between
different repertoires. Finally, extensive use of attributes and
clearly-defined classification mechanisms in the schema permits the
refinement of element meanings within specific musical, geographic, or
126.96.36.199Control and Maintenance
The Music Encoding Initiative Community has given itself By-laws, which regulate all essential properties and procedures.
The community elects a Board,
which in turn governs and represents the community. The Board consists of
nine elected members, with three seats standing for election for three year
terms each year. Everyone registered to the MEI-L mailing list is eligible to vote for the Board.
In addition to the Board, there is a Technical Team, which is open for anyone interested to work on the
maintenance and improvement of MEI itself. The Technical team will assist
Interest Groups and other interested community members in an advisory
capacity on how to further develop MEI for both existing and new fields of
Many institutions and individuals assisted in the preparation of these
Guidelines and in the overall development of the Music Encoding Initiative
framework and community.
Grateful acknowledgment is given to the following institutions for their
generous contributions: the Akademie der Wissenschaften und der Literatur (AdW)
in Mainz for serving as hosting institution for the MEI Community, and the
National Endowment for the Humanities (NEH) and the Deutsche
Forschungsgemeinschaft (DFG) for their joint financial support of the MEI
project in its early stages. We thank several institutions that hosted Music
Encoding Conferences or other MEI-related meetings in the past: The AdW Mainz,
the University of Virginia Library, the Biblioteca Umanistica of the
Università degli Studi Firenze, McGill University Montréal, the Centre
d’études supérieures de la Renaissance Tours, the Maryland Institute for
Technology in the Humanities (MITH) in College Park, the Oxford e-Research
Centre, the Universität Paderborn and the Österreichische Akademie der
Wissenschaften Wien in conjunction with the Universität Wien and the Mozarteum
Salzburg. We also thank all other institutions that allow their researchers to
invest time into both the community and the encoding framework. It is their
interest that makes MEI an incredible platform for interchange and scholarly
The Text Encoding Initiative is also owed a special debt of gratitude. In
addition to providing much of the inspiration for MEI, the TEI organization
supplied funding for the MEI Technical Group in its efforts to adopt ODD. The
editors of these Guidelines are grateful for those of the TEI, which provided a
stellar exemplar and from which we have borrowed shamelessly.
MEI has been a community-driven effort for more than a decade, and many
individuals have provided significant and much-appreciated commitments of time
and energy to the development of MEI: Nikolaos Beer; Vincent Besson; Benjamin
W. Bohl; Margrethe Bue; Donald Byrd; Irmlind Capelle; Tim Crawford; David A.
Day; Giuliano Di Bacco; Norbert Dubowy; Richard Freedman; Ichiro Fujinaga;
Andrew Hankinson; Maja Hartwig; Kristin Herold; Franz Kelnreiter; Johannes
Kepper; Robert Klugseder; Zoltán Kömíves; David Lewis; Urs Liska; Elsa De Luca;
Erin Mayhood; Stefan Morent; Stefan Münnich; Markus Neuwirth; Kevin Page;
Daniel Pitti; Laurent Pugin; Klaus Rettinghaus; Kristina Richts; Daniel
Röwenstrunk; Perry Roland; Craig Sapp; Agnes Seipelt; Eleanor Selfridge-Field;
Christine Siegert; Peter Stadler; Axel Teich Geertinger; Martha Thomae; Joachim
Veit; Raffaele Viglianti; Thomas Weber; and Sonia Wronkowska.
Thanks to Bernhard R. Appel; Richard Chesser; Morgan Cundiff; J. Stephen
Downie; Oliver Huck; Fotis Jannidis; John Rink; Federica Riva; Frans Wiering
and Barbara Wiermann for providing expertise on a wide range of topics related
to music notation modelling.
Also thanks to Syd Bauman, Terry Catapano, and Sebastian Rahtz for their
invaluable problem-solving assistance during the development of the 2010 RNG
schema. Thanks to Sebastian Rahtz and James Cummings of the Text Encoding
Initiative (TEI) for their help with making ODD work with MEI, their assistance
in more closely aligning MEI and TEI, and their quick responses to questions
and Roma bug reports.
Finally, the members of the Music Encoding Initiative would like to thank Perry
Roland for his foresight, engagement and dedication in laying the foundations
of this initiative.
1.2Basic Concepts of MEI
This chapter is intended to explain basic concepts of MEI, like events vs.
The term "music" has many different notions, ranging from audible sounds over
written performance instructions or transcriptions of such events to conceptual
rulesets that establish different theories of what music is, and what is
allowed in music. In 1965, Milton Babbitt distinguished between graphemic, acoustic and auditory aspects of music (Babbitt, Milton: The Use of Computers in Musicological Research, in: Perspectives of New Music 3/2 (1965), p. 76).
Various music encoding formats took up this distinction, most notably SMDL, the
Standard Music Description Language (ISO/IEC DIS
10743). While the format itself was hardly ever used for its impractical
implementation details, parts of its design certainly influenced the
development of other formats, including MEI. In a documentation draft (http://xml.coverpages.org/smdl10743-pdf.gz, p.5), SMDL identifies
four different musical domains:
The logical domain is the basic musical content – the essence from which
all performances and editions of the work are derived, including virtual
time values, nominal pitches, etc. The logical domain is describable as “the
composer’s intentions with respect to pitches, rhythms, harmonies, dynamics,
tempi, articulations, accents, etc.,” and it is the primary focus of SMDL.
It can also be described as “the abstract information common to both the
gestural and visual domains.” […]
The gestural domain is comprised of any number of performances, each of
which may specify how and when components of the logical domain is rendered
in a specific performance, including all the means whereby the performer
actually “expresses” (acoustically instantiates) the music (intonation,
agogic and dynamic stress, etc.). The gestural domain is perhaps most
succinctly described as “the information added by performers,” or “how the
music actually sounds during particular performances.” […]
The visual domain is comprised of any number of scores, each of which
somehow specifies exactly how components of the logical domain is rendered
visually in some particular printable (and/or displayable) edition,
including such graphical details as symbology, symbol sets, fonts, page
layout, beaming conventions and exceptions, etc. The visual domain is
perhaps most succinctly described as “the information added by human
editors, engravers, and typesetters,” or “how the music actually looks in
some particular edition.” […]
The analytical domain is comprised of any number of theoretical analyses
and/or commentaries, each of which somehow specifies opinions, exegeses,
etc. about any or all of the information in the other three domains.
On a generic level, MEI follows the same definition, and it definitely shares
the same terminology. However, not all four domains are available throughout
the MEI schema, and quite frequently, two domains fall together in MEI. Very
often, MEI prioritizes the visual domain over the gestural domain by (partly)
conflating the logical and the visual domains. For example, MEI utilizes the
pname (pitch name) attribute on notes to capture the written
pitch of a note, whereas the sounding pitch may be described with the
pname.ges attribute. Here, the logical and visual domains go
without a special indication, whereas the gestural domain is identified by a
special suffix. However, in case of transposing instruments, additional markup
(namely the attributes trans.diat and trans.semi from
MEI's attribute class att.staffDef.log) will create
a distinction between the logical and visual domain (see chapter 4.2.2 Defining Score Parameters for CMN). In that case, pname will be restricted to
the visual domain, while the logical aforementioned attributes provide
additional information for the logical domain.
Even though the technical implementation of MEI prioritizes the visual domain
to some degree, this does not mean that any given encoding has to provide
visual information. MEI takes no assumption on what data is required: While an
OMR project (optical music recognition) may generate strictly visually
oriented data only, another project focussed on audio transcriptions may
generate gestural data only. A third project could integrate both
In order to avoid ambiguous encodings, MEI is very strict and specific on the
scope of its individual markup elements. For an encoder, the suffixes mentioned
above provide clear hints on which domain is addressed by specific markup: Many
attributes carry a suffixed .log (logical), .ges (gestural), .vis
(visual), or .anl (analytical) in their name. In addition, the internal
structure of MEI heavily relies on those different domains. When customizing
MEI (see chapter 1.2.5 Customizing MEI), it is possible to turn off
either visual or gestural domain encoding completely. That way, MEI allows to
address the four most eminent musical domains specifically and independent of
1.2.2Events and Controlevents
MEI differentiates between two essential aspects of music notation: Events and ControlEvents. There
are other examples for such a separation of concerns with regard to music. In
Greg's Copy-Text Theory (W.W.Greg: The Rationale of
Copy-Text, 1950), a distinction between primary and secondary text is
made; similar attempts have been made for music specifically.
In MEI, elements describing the basic musical text are referred to as Events. They are the building blocks for the stream of
music – mostly those are notes, rests, and chords. In contrast, ControlEvents make no independent contribution to that
flow of music. Instead, they provide additional information about the encoded
Events, they control their
performance. Examples for such ControlEvents are dynamic markings, tempos
indications, or performance directives. Depending on the
encoding strategy used, slurs and ties often also fall into this category (they may be encoded as
attributes instead, in which case they become a property of the basic events).
Simply put, Events describe what needs to be performed, and ControlEvents
indicate how it needs to be performed. In (4 Repertoire: Common Music Notation-based) MEI, Events are nested inside
a layer element, while ControlEvents are direct children of the first measure they apply to, following all staff
elements there. These structural differences result in different markup
concepts. As Events are encoded inside layers, their semantic position inside the
encoded work can be derived from their structural
position – the measure, staff and layer they're nested in, and within
that layer by their position inside the sequence of all layer children. As
mentioned above, it is highly recommended to encode ControlEvents inside the first measure they apply to, but
they still require references to the actual events they apply to. There are two
common concepts to provide such a connection, both of which offering specific
benefits and drawbacks. A technically very stable connection between ControlEvents and Events can be
established by using pointers. In this case, all events
that need to be referenced need an xml:id attribute, which holds a
globally unique identifier for this very element. The referencing controlevent
then uses a startid and, if necessary, endid attribute to
create a link to where in the stream of music it is supposed to start or
In the example above, the dynam element references the
second quarter in the given measure. Additional attributes like
place may be used to describe the position of the forte indication within the score. A hairpin element may use the endid attribute to indicate the
duration of the hairpin using the same mechanism as above.
Indicates the final element in a sequence of events to which the feature
A ControlEvent encoded like above will be strictly tied
to the referenced Events – if their position inside the
XML document changes for whatever reason, they will keep that connection. This
means that the semantic position to which they are bound
may change without affecting the binding. An example could be an inserted
additional note in front – the dynamic marking would not start on the second
quarter, but perhaps on the third instead.
As this behavior may not be desired in all cases, an alternative binding
between ControlEvents and Events
is possible, relying on timestamps instead. This
mechanism is illustrated in the following example:
Here, no xml:id is required on notes. Instead, the dynam element uses the staff and layer
attributes to indicate to which set of events the following tstamp
attribute refers to.
Encodes the onset time in terms of musical time, i.e., beats[.fractional beat part],
as expressed in the written time signature.
This mechanism actually depends on what has been only recommended above:
placing the controlevent inside the measure where it starts. The
startid reference mechanism would work equally well if all
controlevents where positioned in the very first or last measure, or actually
even inside a separate file. The tstamp references however would
not, they depend on correct placement of the controlevents inside the XML tree.
For consistency, it is therefore recommended to always
use this placement.
The benefit of this concept is that controlevents are tied to a semantic position, but not necessarily to a given XML
element. The forte may still be placed on the second
quarter, even though the composer may have replaced that quarter G4 with a
different pitch and / or duration. Actually, it is not required that an Event can be found at the position indicated by a
timestamp. This may be useful to encode a slur ending at an arbitrary position
between two events, or dynam markings spread across otherwise empty
If the ending of a ControlEvent shall be given by
timestamp, the tstamp2 attribute is used.
Encodes the ending point of an event, i.e., a count of measures plus a beat location
in the ending measure.
Because of potential inconsistencies, an encoding should not offer both
startid and tstamp or endid and
tstamp2. Though not being recommendable, it is possible to mix
startid with tstamp2 and tstamp with
endid. In general, it is easier for software to process
startid and endid. When no other arguments apply,
using xml:id-based pointers is therefore the most common way to
connect ControlEvents with Events.
In MEI, timestamps are treated in a slightly simplified way: they have no
notion of beat. Instead, timestamps rely solely on the
numbers given in the meter signature. In a measure of 4/4, timestamps will
range from 1 to 4. The second eighth note will be 1.5 in this case. If the same
measure would be given in 2/2, it would be 1.25 instead.
Encodes the onset time in terms of musical time, i.e., beats[.fractional beat part],
as expressed in the written time signature.
At this point, MEI uses real numbers only to express timestamps. In case of
(nested or complex) tuplets, this solution is inferior to fractions because of
rounding errors. It is envisioned to introduce a fraction-based value for
timestamps in a future revision of MEI. For now, it is recommended to round the
fractional part of the number to no more than five digits to avoid such
Durations may also be expressed based on timestamps. In this case, the values
are a combination of the count of measures that need to
be moved forward to reach the measure in which an encoded feature ends, and the
timestamp within that measure.
Encodes the ending point of an event, i.e., a count of measures plus a beat location
in the ending measure.
The following example contains a number of slur examples
illustrating durations expressed by timestamps.
Sometimes, timestamps are used to indicate positions where no music Events are located (see 1.2.2 Events and Controlevents). Therefore, the allowed range of timestamps
stretches from 0 to the current meter count + 1. By definition, a timestamp of
1 indicates the position of the left barline, while a timestamp of 5 (in case
of a 4/4 meter) indicates the right barline. This makes it possible to encode
open-ended slurs in a graphical way. However, it should be kept in mind that
such timestamps may not be converted to startid and
endid, and not every application may be able to render them
correctly, even though they are perfectly valid MEI, and sometimes are
necessary to faithfully transcribe a source.
MEI is an encoding framework, not a data format. This means that MEI provides
recommendations for encoding music documents, but it depends on the encoder's
needs and requirements to which features and solutions are appropriate to the
task and should to be used. MEI offers specific models for different notation
types and music repertoires, but it is rarely advisable to use them all side by
side in one encoding.
In order to use MEI, it is advised to use a restricted version of the schema,
which will make it easier both for an encoder and a reader of the encoded
files. MEI provides a number of pre-defined profiles, which focus on specific
uses of MEI while still maintaining a great level of flexibility. For projects
that need even better control over their data, it is highly recommended to
create a more specific customized version of MEI (see chapter 1.2.5 Customizing MEI). The following customizations are provided
with every release of MEI:
For most users, this will be the best starting point into music
encoding with MEI. The mei-CMN customization targets at documents that use
Common Western Music Notation. The specific rules for that notation are
specified in chapter 4 Repertoire: Common Music Notation, even though other chapters of these
Guidelines apply as well.
For documents written in Mensural Notation (both black and
white), MEI offers the mei-Mensural customization. The specific rules for
that notation are specified in chapter 5 Repertoire: Mensural Notation, even though
other chapters of these Guidelines apply as well.
This profile allows to encode medieval Neume Notation with MEI.
The specific rules for that notation are specified in chapter 6 Repertoire: Neume Notation, even though other chapters of these Guidelines apply as
well. Please note that the mei-Neumes profile has undergone significant
changes from MEI version 3 to version 4.
As an encoding framework, MEI offers multiple approaches to encode
certain features at various levels of detail. While this flexibility is at the
core of MEI and often required for research projects, it is an obstacle when
developing software and converters for MEI. The mei-Basic profile is a subset
of MEI which restricts it to one way of encoding for every feature of music
notation. It covers Common Western Music Notation only, and excludes all
editorial markup. In essence, it has the same functionality as most other music
encoding formats like MusicXML or MNX. The purpose of mei-Basic is to serve
as common ground for data interchange, both between projects using different
profiles of MEI, and other encoding schemes.
This is the full definition of MEI. It includes all different
repertoires, which has certain side effects and enables encoding options that
are neither intended nor advocable. For example, in mensural notation music is
organized by staves. In contrast, Common Music Notation utilizes measures,
which in turn contain staves. These staves have a different meaning here, and
are modeled differently in MEI. mei-all mixes those models and thus invites
encoding errors. In general, you should almost never use mei-all except for
This profile includes all of mei-all, but extends it even
further so that it allows any MEI element as root of conforming MEI instances.
In regular MEI, the only allowed starting elements are mei, meiHead, music and
meiCorpus. The sole purpose of this customization is
to simplify validation at tutorial sessions and other educational purposes. It
should not be used in production.
The first three profiles provide good starting points to encode music from the
respective repertoires. They may also serve as template for further,
project-specific customizations. The latter two profiles are targetting very
specific use cases and should not be used by default.
In production, it is best to use a customized version of MEI, restricted to the
very needs of a project. Such a custom schema will guide the encoders and will
help to ensure consistency and data quality throughout a project's files. A
customization typically provides a subset of MEI's encoding models (typically
starting from one of the official profiles mentioned in chapter 1.2.4 MEI Profiles), with only one solution for any given situation
being allowed. The customization will help to reflect the scope of a project
into its data: Only those aspects of music notation a project is interested in
will be allowed, so that the absence of a specific information can not be
misunderstood as an oversight of the encoders. Larger editorial projects like
Complete Works editions typically use Editorial Guidelines (german:
Editionsrichtlinien) for the same purposes: (internal) quality control and
(external) documentation. In that sense, MEI customizations may serve as
Editorial Guidelines in digital form.
MEI provides a webservice at http://custom.music-encoding.org which allows to
compile such customizations against the MEI sources in order to generate
RelaxNG schemata, which can be used for validation. More documentation on
customizing MEI will be provided as time permits; until then, it is recommended
to reach out to the MEI Community for additional