Several of the following definitions of terms have been borrowed or
            modified from similar definitions in documents originating from W3C or
            standards organizations. See the individual definitions for more
            information.
         
         
            - Argument
            
- A child of a presentation layout schema. That is, "A is an
               argument of B" means "A is a child of B and B is a
               presentation layout schema". Thus, token elements have no arguments,
               even if they have children (which can only be 
               malignmark).
- Attribute
            
- A parameter used to specify some property of an SGML or XML element
               type. It is defined in terms of an attribute name, attribute type, and a
               default value.  A value may be specified for it on a start-tag for that
               element type.
            
- Axis
            
- The axis is an imaginary alignment line upon which a fraction line
               is centered. Often, operators as well as characters that can stretch, such
               as parentheses, brackets, braces, summation signs etc., are centered on
               the axis, and are symmetric with respect to it.
            
- Baseline
            
- The baseline is an imaginary alignment line upon which a glyph
               without a descender rests.  The baseline is an intrinsic property of the
               glyph (namely a horizontal line). Often baselines are aligned (joined)
               during typesetting.
            
- Black box
            
- The bounding box of the actual size taken up by the viewable
               portion (ink) of a glyph or expression.
            
- Bounding box
            
- The rectangular box of smallest size, taking into account the
               constraints on boxes allowed in a particular context, which contains some
               specific part of a rendered display.
            
- Box
            
- A rectangular plane area considered to contain a character or
               further sub-boxes, used in discussions of rendering for display. It is
               usually considered to have a baseline, height, depth and width.
            
- Cascading Style Sheets (CSS)
            
- A language that allows authors and readers to attach style
               (e.g. fonts, colors and spacing) to HTML and XML documents.
            
- Character
            
- A member of a set of identifiers used for the organization, control
               or representation of text. ISO/IEC Standard 10646-1:1993 uses the word
               "data" here instead of "text".
            
- Character data (CDATA)
            
- A data type in SGML and XML for raw data that does not include
               markup or entity references. Attributes of type CDATA may contain
               entity references. These are expanded by an XML processor before the
               attribute value is processed as CDATA.
            
- Character or expression depth
            
- Distance between the baseline and bottom edge of the character
               glyph or expression. Also known as the descent.
            
- Character or expression height
            
- Distance between the baseline and top edge of the character glyph
               or expression. Also known as the ascent.
            
- Character or expression width
            
- Horizontal distance taken by the character glyph as indicated in
               the font metrics, or the total width of an expression.
            
- Condition
            
- A MathML content element used to place a mathematical condition on
               one or more variables.
            
- Contained (element A is contained in element B)
            
- A is part of B's content.
- Container (Constructor)
            
- A non-empty Content MathML element that is used to construct a
               mathematical object such as a number, set, or list.
            
- Content elements
            
- MathML elements that explicitly specify the mathematical meaning
               of a portion of a MathML expression (defined in Chapter 4 Content Markup).
            
- Content token element
            
- Content element having only PCDATA, sepand presentation expressions as content. Represents either an identifier
               (ci) or a number (cn).
- Context (of a given MathML expression)
            
- Information provided during the rendering of some MathML data to
               the rendering process for the given MathML expression; especially
               information about the MathML markup surrounding the expression.
            
- Declaration
            
- An instance of the declare element.
- Depth
            
- (of a box) The distance from the baseline of the box to the bottom
               edge of the box.
            
- Direct sub-expression
               (of a MathML expression "E")
            
- A sub-expression directly contained in E.
- Directly contained
               (element A in element B)
            
- A is a child of B (as defined in XML), in other words
               A is contained in B, but not in any element that is itself contained in
               B.
            
- Document Object Model
            
- A model in which the document or Web page is treated as an object
               repository. This model is developed by the DOM Working Group (DOM) of the
               W3C.
            
- Document Style Semantics and Specification Language (DSSSL)
            
- A method of specifying the formatting and transformation of
               SGML documents. ISO International Standard 10179:1996.
            
- Document Type Definition (DTD)
            
- In SGML or XML, a DTD is a formal definition of the elements and
               the relationship among the data elements (the structure) for a particular
               type of document.
            
- Em
            
- A font-relative measure encoded by the font. Before electronic
               typesetting, an "em" was the width of an
               "M" in the font. In modern usage, an "em"
               is either specified by the designer of the font or is taken to be the
               height (point size) of the font. Em's are typically used for font-relative
               horizontal sizes.
            
- Ex
            
- A font-relative measure that is the height of an "x"
               in the font.  "ex"s are typically used for
               font-relative vertical sizes.
            
- Height
            
- (of a box) The distance from the baseline of the box to the top
               edge of the box.
            
- Inferred mrow
- An mrowelement that is
               "inferred" around the contents of certain layout schemata when
               they have other than exactly one argument. Defined precisely in Section 3.1.9 Summary of Presentation Elements
- Embedded object
            
- Embedded objects such as Java applets, Microsoft Component Object
               Model (COM) objects (e.g. ActiveX Controls and ActiveX Document
               embeddings), and plug-ins that reside in an HTML document.
            
- Embellished operator
            
- An operator, including any "embellishment" it may
               have, such as superscripts or style information. The
               "embellishment" is represented by a layout schema that
               contains the operator itself.
               Defined precisely in Section 3.2.5 Operator, Fence, Separator or Accent
                  <mo>.
- Entity reference
            
- A sequence of ASCII characters of the form &name;representing some other data, typically a
               non-ASCII character, a sequence of characters, or an external source of
               data, e.g. a file containing a set of standard entity definitions such as
               ISO Latin 1.
- Extensible Markup Language (XML)
            
- A simple dialect of SGML intended to enable generic SGML to be
               served, received, and processed on the Web.
            
- Fences
            
- In typesetting, bracketing tokens like parentheses, braces, and
               brackets, which usually appear in matched pairs.
            
- Font
            
- A particular collection of glyphs of a typeface of a given size,
               weight and style, for example "Times Roman Bold 12 point".
            
- Glyph
            
- The actual shape (bit pattern, outline) of a character.
               ISO/IEC Standard 9541-1:1991 defines a glyph as a recognizable abstract 
               graphic symbol that is independent of any specific design.
            
- Indirectly contained
            
- A is contained in B, but not directly contained in B.
- Instance of MathML
            
- A single instance of the top level element of MathML, and/or a
               single instance of embedded MathML in some other data format.
            
- Inverse function
            
- A mathematical function that, when composed with the original
               function acts like an identity function.
            
- Lambda expression
            
- A mathematical expression used to define a function in terms of
               variables and an expression in those variables.
            
- Layout schema (plural: schemata)
            
- A presentation element defined in chapter 3, other than the token
               elements and empty elements defined there (i.e. not the elements defined in
               Section 3.2 Token Elements and Section 3.5.5 Alignment Markers
                  <maligngroup/>,<malignmark/>, or the
               empty elementsnoneandmprescriptsdefined in Section 3.4.7 Prescripts and Tensor Indices<mmultiscripts>,<mprescripts/>,<none/>).
               The layout schemata are never empty elements (though their content may
               contain nothing in some cases), are always expressions, and all allow any
               MathML expressions as arguments (except for requirements on argument count,
               and the requirement for a certain empty element inmmultiscripts).
- Mathematical Markup Language (MathML)
            
- The markup language specified in this document for describing
               the structure of mathematical expressions, together with a mathematical
               context.
            
- MathML element
            
- An XML element that forms part of the logical structure of a
               MathML document.
            
- MathML expression (within some valid MathML
               data)
            
- A single instance of a presentation element, except for the empty
               elements noneormprescripts, or an instance ofmalignmarkwithin a token element (defined below);
               or a single instance of certain of the content elements
               (see Chapter 4 Content Markup for a precise definition of which ones).
- Multi-purpose Internet Mail Extensions (MIME)
            
- A set of specifications that offers a way to interchange text in
               languages with different character sets, and multimedia content among many
               different computer systems that use Internet mail standards.
            
- Operator, content element
            
- A mathematical object that is applied to arguments using the 
               applyelement.
- Operator, an moelement
- Used to represent ordinary operators, fences, separators in MathML
               presentation. (The token element mois defined in
               Section 3.2.5 Operator, Fence, Separator or Accent<mo>).
- OpenMath
            
- A general representation language for communicating mathematical
               objects between application programs.
            
- Parsed character data (PCDATA)
            
- An SGML/XML data type for raw data occurring in a context where
               text is parsed and markup (for instance entity references and element
               start/end tags) is recognized.
            
- Point
            
- Point is often abbreviated "pt". The value of 1 pt 
               is approximately 1/72 inch. Points are typically used to specify
               absolute sizes for font-related objects.
            
- Presentation elements
            
- MathML tags and entities intended to express the syntactic
               structure of mathematical notation (defined in Chapter 3 Presentation Markup).
            
- Presentation layout schema
            
- A presentation element that can have other MathML elements as
               content.
            
- Presentation token element
            
- A presentation element that can contain only parsed character data
               or the malignmarkelement.
- Qualifier
            
- A MathML content element that is used to specify the value of a
               specific named parameter in the application of selected pre-defined
               functions.
            
- Relation
            
- A MathML content element used to construct expressions such as
               a < b.
            
- Render
            
- Faithfully translate into application-specific form allowing native
               application operations to be performed.
            
- Schema
            
- Schema (plural: schemata or schemata). See "presentation layout
               schema".
            
- Scope of a declaration
            
- The portion of a MathML document in which a particular
               definition is active.
            
- Selected sub-expression
               (of an mactionelement)
- The argument of an mactionelement (a
               layout schema defined in Section 3.7 Enlivening Expressions) that is (at any
               given time) "selected" within the viewing state of a MathML
               renderer, or by theselectionattribute when the
               element exists only in MathML data. Defined precisely in the aforementioned
               section.
- Space-like (MathML expression)
            
- A MathML expression that is ignored by the suggested rendering
               rules for MathML presentation elements when they determine operator forms
               and effective operator rendering attributes based on operator positions in
               mrowelements. Defined precisely in Section 3.2.7 Space<mspace/>.
- Standard Generalized Markup Language (SGML)
            
- An ISO standard (ISO 8879:1986) that provides a formal
               mechanism for the definition of document structure via DTDs (Document
               Type Definitions), and a notation for the markup of document instances
               conforming to a DTD.
            
- Sub-expression (of a MathML expression
               "E")
            
- A MathML expression contained (directly or indirectly) in the
               content of E.
            
- Suggested rendering rules for
               MathML presentation elements
            
- Defined throughout Chapter 3 Presentation Markup; the ones that use other
               terms defined here occur mainly in Section 3.2.5 Operator, Fence, Separator or Accent
                  <mo>and in
               Section 3.7 Enlivening Expressions.
- TEX
            
- A software system developed by Professor Donald Knuth for
               typesetting documents.
            
- Token element
            
- Presentation token element or a Content token element.  (See
               above.)
            
- Top-level element (of MathML)
            
- math(defined in Section 2.2 The Top-Level- <math>Element).
- Typeface
            
- A typeface is a specific design of a set of letters, numbers and
               symbols, such as "Times Roman" or "Chicago".
            
- Valid MathML data
            
- MathML data that (1) conforms to the MathML DTD, (2) obeys the
               additional rules defined in the MathML standard for the legal contents and
               attribute values of each MathML element, and (3) satisfies the EBNF grammar
               for content elements.
            
- Width (of a box)
            
- The distance from the left edge of the box to the right edge of the
               box.
            
- Extensible Style Language (XSL)
            
- A style language for XML developed by W3C. See XSL FO and XSLT.
- XSL Formatting Objects (XSL FO)
            
- An XML vocabulary to express formatting, which is a part of XSL.
- XSL Transformation (XSLT)
            
- A language to express the transformation of XML documents
               into other XML documents.