 |  | Copyright © 1992, 1997 International Organization for Standardization. All rights reserved. This electronic document is for use during development and review of International Standards. Official printed copies of International Standards can be purchased from the ISO and the national standards organization of your country. | ||
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A dimension specification represents a coordinate location on a single axis (see 6.8 Coordinate Specifications). When the scheduling module of HyTime is used, finite coordinate spaces with multiple axes can be defined.
An "extent specification" represents a coordinate location or "bounding box" on all of the axes of a finite coordinate space and consists of one dimension specification per axis.
The set of first quanta of each dimension specification of an extent defines the position of the bounding box. The set of quantum counts for all the dimension specifications defines its size.
NOTE 273 The bounding box need not be rectangular, as HyTime makes no assumptions as to the relationship, if any, between the coordinate axes. However, as HyTime's principal field of application deals with coordinate spaces that can be rendered perceivable by humans, use of terminology that implies orthogonal axes seems justified.
HyTime offers an application a construct for collecting and aligning extents called a "schedule". A schedule allows the application to define the order in which dimensions will be specified (that is, the order of the axes).
A schedule is a list of elements, each having a dimension on all axes of the coordinate space in which the schedule occurs or to which it refers. HyTime defines three kinds of schedules: event schedules, wands, and batons; these elements use the schedule (sched) attribute form.
The attribute governing fcs element (fcs) refers to the fcs element that defines the logical FCS within which the scheduled elements occur. If the fcs attribute is not specified, the schedule must be a subelement of an fcs element and is a schedule of the logical FCS corresponding to that fcs element.
The attribute axis order (axisord) specifies the order of axes for extent specification within the schedule if they are different from the order the axes are specified by the axes attribute of the governing fcs element. If at least one axis name is specified, omitted axis names mean all elements in the schedule fully occupy the omitted axes. For each axis name specified, an attribute of the same name may be used to specify the HMU for the axis. The lexical type of such attributes is (ratio, granule?), where the ratio is the number of HMUs per base granule, and the granule, if specified, is the base granule. If a granule is not specified, the default base granule defined by the governing fcs element is used. A specified granule must be defined in terms of the axis SMU. If a value is not supplied for an axis HMU specification attribute, the HMU for that axis is the default HMU defined by the governing fcs element.
The attribute sorted (sorted) specifies whether the order of the SGML representation of the elements in the schedule is sorted. If so, elements with multiple scheduled extents must have their extents sorted, and the elements are sorted by their first extents. The sort order is by position on the axes, in the order specified by the axis order attribute, with the first specified axis being the primary sort key, the second axis the secondary key, and so on.
The attribute extent coverage (coverage) specifies whether or not gaps may occur between the scheduled extents of elements in the schedule.
The attribute extent overlap (overlap) specifies whether or not scheduled extents of elements in the schedule may overlap. If the schedule is a wand, the value of the overlap attribute is ignored and treated as if it were "noverlap".
NOTE 274 The extents of the modscopes on a given wand are never permitted to overlap.
<!-- Schedule -->
<![ %sched; [
<!attlist
-- sched -- -- Schedule --
-- Clause: 9.4.1 --
(baton,evsched,wand)
fcs -- Governing finite coordinate space element --
CDATA -- Reference --
-- Reftype: fcs --
#IMPLIED -- Default: containing fcs element --
-- Constraint: required if schedule is not contained
by fcs element. --
axisord -- Axis order --
-- The order of axes for extent specification within
schedule. For each axis name specified, an
attribute of the same name may be used to specify
the HMU for the axis. The lexical type of such
attributes is (ratio, granule?), where the ratio
is the number of HMUs per base granule, and the
granule, if specified, is the base granule. If a
granule is not specified, the default base
granule defined by the governing fcs element is
used. A specified granule must be defined in
terms of the axis SMU. If a value is not
supplied for an axis HMU specification attribute,
the HMU for that axis is the default HMU defined
by the governing fcs element. --
CDATA -- Lextype: (AXISNM)+ --
-- Constraint: axis names must be defined by
governing fcs element --
#IMPLIED -- Constant --
-- Default: Axis order is unchanged from that
specified by governing fcs element, and each axis
may have an HMU specification attribute. --
sorted -- Extent ordering --
-- Ordering of elements with respect to the ordering
of their scheduled extents. --
(sorted|unsorted)
unsorted
coverage -- Extent coverage --
-- Whether or not gaps may occur between the
scheduled extents of elements in the schedule. --
(solid|sparse)
sparse
overlap -- Extent overlap --
-- Whether or not scheduled extents of elements in
the schedule may overlap. --
-- Constraint: If the schedule is a wand, the value
is ignored and is always treated as noverlap. --
(overlap|noverlap)
#IMPLIED -- Default: If the schedule is not a wand, the
default value is overlap. --
>
]]><!-- sched -->The attribute form exspec consists of the single attribute nominal extent specification (exspec), which associates a scheduled extent (or extents) with an element. Multiple scheduled extents can be specified if it is desired to represent the cloning or repetition of the element in more than one position and/or in different sizes.
NOTE 275 The semantic of having multiple extents for a single event is not defined. This means that an application can be defined in such a way that the object scheduled by an event is somehow divided among the extents, or that the object is duplicated, with one whole copy for each extent, or some combination of the two. There are many other possibilities, as well, with many possible refinements.
<!-- Extent Specification -->
<![ %sched; [
<!attlist
-- exspec -- -- Nominal extent specification --
-- Clause: 9.4.2 --
(event,modscope,proscope)
exspec -- Extent specification --
CDATA -- Reference --
-- Reftype: (extent|extlist)+ --
#REQUIRED
>
]]><!-- sched -->Events, modscopes, and proscopes can appear within the syntactic container elements evgrp, modgrp, and progrp, respectively. These container elements can appear within evscheds, wands, and batons, respectively, along with events, modscopes, and proscopes that are not contained in evgrps, modgrps, and progrps. Moreover, evgrps, modgrps, and progrps are recursive. The semantic significance of containment within groups is primarily defined by the application. However, the grpdex, repscope, and axis-named attributes of the group derived extent specification (grpdex) and group repetition specification (grprepet) attribute forms, which are used only in the evgrp, modgrp, and progrp element forms, carry HyTime-defined semantics which can be used to make the effective extents of the elements contained by them proportional to, and/or translations of, their nominal extents (grpdex), to specify an area in which the group is repeated (repscope), and to specify other criteria governing repetition and the calculation of the "first" component of a dimension of the syntactically succeeding event, modscope, and proscope, if any, that is expressed using the implicit dimref feature.
The attribute group derived extent specification (grpdex), if specified, specifies one or more derived extents of the group. A subelement with more than one nominal scheduled extent will be given a derived extent for each scheduled extent.
Multiple derived extents can be used to represent repetitions with varying proportions and translations: the group's subelements are positioned in the FCS in each of the derived extents. The application defines the semantics applied when events have multiple distinct extents, e.g., whether the object of the event is duplicated among all the extents, or whether it is somehow distributed among them. However, each distinct extent of a modscope or proscope is treated as if it were a distinct modscope or proscope, with the entire modifier or projector brought to bear by each one.
If a value is specified for the grpdex attribute, for each axis, a matrix calculation is performed for each nominal dimension of each nominal extent against each dimension of each extent specified by the grpdex attribute, in which a set of derived effective dimensions is calculated for each nominal dimension of each extent of each contained element by calculating a derived first quantum and quantum count according to the following formulas:
DerivedFirstQuantum = GrpdexFirstQuantum +
(((NominalFirstQuantum - GroupScopeFirstQuantum)
* GrpdexQcnt) / GroupScopeQcnt)
DerivedQcnt = (NominalQcnt * GrpdexQcnt) / GroupScopeQcntwhere DerivedFirstQuantum and DerivedQcnt are the "first" and "qcnt"
components, respectively, of each derived dimension;
NominalFirstQuantum and NominalQcnt are the "first" and "qcnt"
components, respectively, of each nominal dimension of each extent of
each contained element; GroupScopeFirstQuantum and GroupScopeQcnt are
the "first" and "qcnt" components, respectively, of the dimension of
the "group scope" (the sum of the extents of the subelements of the
group, less any overlap and including any gaps, or, in other words, on
each axis, the dimension bounded by the first quantum of the child
element with the lowest first quantum, at one end, and the last
quantum of the child element with the highest last quantum, on the
other end); and GrpdexFirstQuantum and GrpdexQcnt are the "first" and
"qcnt" components, respectively, of each dimension of each extent
specified by the grpdex attribute. (The asterisks and slashes are
multiplication and division operators, respectively.) The resulting
dimensions are rounded to the nearest whole MDU.If no value is specified for the grpdex attribute, the nominal extents of the contained elements are the effective scheduled extents.
NOTE 276 If a value is specified for the grpdex attribute, and it is desired to retain the nominal scheduled extent of each member in addition to the derived extents, an extent equal to the "group scope" extent must be specified as one of the grpdex extents. (The "group scope" extent is the sum of the extents of the subelements of the group, less any overlap and including any gaps, or, in other words, on each axis, the dimension bounded by the first quantum of the child element with the lowest first quantum, at one end, and the last quantum of the child element with the highest last quantum, on the other end.)
If a value is specified for the repetition scope (repscope) attribute, it is the area within which the contained events, modscopes or proscopes are repeated, subject to additional criteria in the value of each axis-named attribute, if any. For each axis, repetition starts at the first quantum of the repetition scope and continues until the repetition scope is exhausted on each axis.
NOTE 277 Repscope can be used to translate the dimensions of the contained elements.
NOTE 278 The effect of repetition is like repeating patterns on wallpaper or the squares of a chessboard. The repetition of patterns along each axis is not necessarily a single row of repetitions; it may be a row of columns of repetitions.
If no value is specified for the repscope attribute, the first or only occurrence of the group is wherever the effective extent of the group places it, and the number of repetitions is limited only by the repeat count limit parameters of the axis-named attributes.
The grprepet attribute form also has optional attributes, one for each axis and having the same name as the axis for which it specifies repetition parameters. Each such attribute is CDATA #IMPLIED, and conforms to the lexical model:
(uint, (("PART"|"NOPART"), unzi)?, unzi?))where the unsigned integer (uint) is the "repeat count limit"
parameter, the specification of "part" or "nopart" ("PART"|"NOPART")
is the "allow partial dimensions" parameter, the following unsigned
nonzero integer (unzi) is the "start point within pattern" parameter,
and the final unsigned nonzero integer (unzi) is the "offset to next
occurrence" parameter.If the value of the repeat count limit parameter is 0, there is no repeat count limit. The group is repeated on this axis from the beginning to the end of the dimension specified by the repscope attribute. If no value is specified for the repscope attribute, the 0 value is treated as if it were 1. If the value of the "repeat count limit" parameter is greater than 0, the number of repetitions is limited to the number specified. If no value is specified for the repscope attribute, the number of repetitions is limited only by the number of repetitions specified and the remaining length of the axis. If no value is specified for an axis-named attribute, the "repeat count limit" parameter is treated as if it were 1.
If the value of the allow partial dimensions parameter is PART, partial repetitions at the beginning and/or end of the series on this axis will be used to completely fill the repetition scope. If the value is NOPART, partial repetitions do not occur. As a result, there may be unoccupied space at the beginning and/or end of the series on this axis within the repetition scope. If no value is specified for this parameter, the group is treated as if the value were "NOPART" for this axis.
The value of the start point within pattern parameter is the number of the HMU within the effective group dimension (where the "first" component of the group's dimension on this axis is considered to be 1) at which the first occurrence in the series begins. If the value is not 1, the remaining partial portion of the group will constitute the first repetition in each series on this axis. This first partial repetition will occur as skipped space if the "allow partial dimensions" parameter's value is "NOPART".
The value of the offset to next occurrence parameter is the number of HMUs that will be treated as the effective qcnt of the group only for purposes of determining the location of the next contiguous repetition, or, in the case of the last or only occurrence of the group, the next dimension with an implicit dimref used as its "first" component. The default value is the effective qcnt of the group.
<!-- Group Derived Extent Specification -->
<![ %grpdex; [
<!attlist
-- grpdex -- -- Group derived extent specification --
-- Clause: 9.4.3 --
(evgrp,modgrp,progrp)
grpdex -- Group derived extent specification --
-- Use for resizing, rearrangement, repetition.
Group members are given the derived extents. If
nominal extent is also wanted, it must be
specified as one of the derived extents. --
CDATA -- Reference --
-- Reftype: (extent|extlist)* --
#IMPLIED -- Default: grpdex is same as overall "group scope",
that is, the nominal extents are effective --
>
<!entity % sched "INCLUDE">
]]><!-- grpdex --> <!-- Group Repetition Specification -->
<![ %grprepet; [
<!attlist
-- grprepet -- -- Group repetition specification --
-- Clause: 9.4.3 --
(evgrp,modgrp,progrp)
repscope -- Repetition scope --
-- Scope within which the contained events,
modscopes or proscopes are repeated, subject to
additional criteria in the value of each
axis-named attribute, if any. For each axis,
repetition starts at the first quantum of the
repetition scope and continues until the
repetition scope is exhausted on each axis. --
CDATA -- Reference --
-- Reftype: extent --
#IMPLIED -- Default: The first or only occurrence of the
group is wherever the effective extent of the
group places it, and the number of repetitions is
limited only by the repeat count limit parameters
of the axis-named attributes. --
-- Additional attributes may be defined for client elements, one for
each axis of the FCS. The names of the attributes are the axis
names, and the values of the attributes are specifications
regarding repetitions of the group and the implicit dimref of the
succeeding extent along an axis. Each of the attributes has the
lexical model (uint,(("NOPART"|"PART"),unzi)?,unzi?), which is
interpreted as follows:
"repeat count limit" parameter (uint):
If the value is 0, there is no repeat count limit. The group
is repeated on this axis from the beginning to the end of the
dimension specified by the repscope attribute. If no value
is specified for the repscope attribute, the 0 value is
treated as if it were 1. If the value of the "repeat count
limit" parameter is greater than 0, the number of repetitions
is limited to the number specified. If no value is specified
for the repscope attribute, the number of repetitions is
limited only by the number of repetitions specified and the
remaining length of the axis. If no value is specified for
an axis-named attribute, the "repeat count limit" parameter
is treated as if it were 1.
"allow partial dimensions" parameter ("PART"|"NOPART"):
If the value is "PART", partial repetitions at the beginning
and/or end of the series on this axis will be used to
completely fill the repetition scope. If the value is
"NOPART", partial repetitions do not occur. (There may be
unoccupied space at the beginning and/or end of the series on
this axis.) The default value is "NOPART".
"start point within pattern" parameter (penultimate unzi):
The value is the number of the HMU (where the "first"
component of the group's dimension on this axis is 1) at
which the first occurrence in the series begins. If the
value is not 1, the remaining partial portion of the group
will constitute the first repetition in each series. This
first partial repetition will occur as skipped space if the
"allow partial dimensions" parameter's value is "NOPART".
The default value is 1.
"offset to next occurrence" parameter (final unzi):
The value is the number of HMUs that will be treated as the
qcnt of the group for purposes of determining the location of
the next contiguous repetition (or the next dimension with an
implicit dimref used as its "first" component). The default
value is the effective qcnt of the group. --
>
<!entity % sched "INCLUDE">
]]><!-- grprepet -->The element form scheduled extent (extent) defines the position and size of elements in schedules. By default, the HyTime extent specification notation is used.
NOTE 279 HyTime treats an extent as a resource, which means that it can occur freely in a document and can be referenced by an ID in the contexts in which it is needed. An application could therefore define "named extent" element types that represent, for example, historical periods, and build a resource pool of "period" elements. An attribute of the period elements would be the name of the period, which an application could use for display or other purposes. Events could be positioned with respect to the periods by means of dimension references (see 9.8 Dimension referencing). Such a pool of period elements would comprise what measurement theory calls an "ordinal scale". Named extents can also be used to construct ordinal scales in domains other than time; for example, shades of color on an axis that represents a portion of the visible spectrum.
NOTE 280 Designers can also require that extent specifications occur in the
content of events by using the refloc facility to address the extent
specification of an event by a tree address relative to the event
element itself. For example, if the client document type sets the
content model of event-form elements to "(extent,
(%event-content;)*)", the tree position "1 1" specified for the exspec
attribute of the event element addresses the extent element that is
its first subelement:
<!ELEMENT event
- - (extent,(%event-content;)*)
>
<!ATTLIST event
HyTime NAME #FIXED event
loctype CDATA #FIXED "exspec treeloc"
-- Tree position of extent subelement --
exspec NUMBERS #FIXED "1 1"
>
<!-- HyTime Extent Specification Notation -->
<![ %HyExSpec; [
<!notation
HyExSpec -- HyTime Extent Specification Notation --
-- Clause: 9.4.4 --
-- A list of dimensions (in the HyTime Dimension
List Notation, after resolution of marker
functions) that together specify a single extent
on one or more axes. --
PUBLIC "ISO/IEC 10744:1997//NOTATION
HyTime Dimension Specification Notation//EN"
-- Attributes [sched]: HyExSpec --
-- CommonAttributes [GenArc]: altreps, included, superdcn --
-- CommonAttributes [base]: bosdatt --
-- CommonAttributes [locs]: egrvplan --
>
<!attlist #NOTATION
HyExSpec -- HyTime Extent Specification Notation --
-- Clause: 9.4.4 --
GenArc NAME #FIXED GABridN
superdcn NAME #FIXED HyDimLst
>
<!entity % HyDimLst "INCLUDE" >
<!entity % sched "INCLUDE">
]]><!-- HyExSpec --> <!-- Extent -->
<![ %sched; [
<![ %HyExSpec; [
<!entity % dexspec "HyExSpec">
]]>
<!entity %
dexspec -- Default extent specification notation --
-- Clause: 9.4.5 --
"#IMPLIED"
>
<!element
extent -- Extent --
-- Clause: 9.4.4 --
-- A position and quantum count along one or more
axes. --
O O
(%HyCFC;|%dimlist;)*
-- Constraint: if no extent specification notation
specified, then content is restricted to
(dimspec)* --
-- Attributes [sched]: extent --
-- CommonAttributes [GenArc]: dafe, dvlatt, etfullnm, id,
ireftype, lextype, opacity --
-- CommonAttributes [base]: activity, conloc, dtxtatt, valueref --
-- CommonAttributes [locs]: refctl, refloc, reftype, rflocspn --
-- Referrers [sched]: dimref:elemspec, exspec:exspec, grpdex:grpdex,
grprepet:repscope --
>
<!attlist
extent -- Extent --
-- Clause: 9.4.4 --
notation -- Extent specification notation --
NAME -- Lextype: NOTATION --
%dexspec; -- Default: content is restricted to (dimspec)* --
>
]]><!-- sched -->The element form scheduled extent list (extlist) specifies a list of extents within a finite coordinate space.
<!-- Extent List -->
<![ %sched; [
<![ %HyExtLst; [
<!entity % dextlist "HyExtLst">
]]>
<!entity %
dextlist -- Default extent list notation --
-- Clause: 9.4.5 --
"#IMPLIED"
>
<!element
extlist -- Extent List --
-- Clause: 9.4.5 --
-- A list of extents on one or more axes. --
O O
(%HyCFC;|%dimlist;|extent|extlist)*
-- Constraint: if no extent list notation
specified, then content is restricted to
(extent|extlist)* --
-- Attributes [sched]: extlist
-- CommonAttributes [GenArc]: dafe, dvlatt, etfullnm, id,
ireftype, lextype, opacity --
-- CommonAttributes [base]: activity, conloc, dtxtatt, valueref --
-- CommonAttributes [locs]: refctl, refloc, reftype, rflocspn --
-- Referrers [sched]: dimref:elemspec, exspec:exspec, grpdex:grpdex --
>
<!attlist
extlist -- Extent List --
-- Clause: 9.4.5 --
notation -- Extent list notation --
NAME -- Lextype: NOTATION --
%dextlist; -- Default: content is restricted to
(extent|extlist)* --
>
]]><!-- sched -->The HyTime extent list notation is an extended form of axis marker list in which dimspecs are derived from the axis markers and extents are then derived from the dimspecs. The list can also contain nested extlists and extents, to any level of nesting, but these will merge to create the effect of a single-level list.
The extent list notation processor must be aware of the number of axes included in the governing axis order of the schedules to which an extent specification applies.
Nested extents and extent lists may be included only at extent specification boundaries within the axis marker list.
NOTE 281 In other words, an extent specification cannot appear within what is effectively another extent specification. A nested element can only appear before or after the dimension specifications for a complete cycle of axes.
<!-- HyTime Extent List Notation -->
<![ %HyExtLst; [
<!notation
HyExtLst -- HyTime Extent List Notation --
-- A list of extents each of which may be specified
as an extent, part of another extent list, or or
as all or part of a list of axis markers
explicitly entered or returned by a marker
function. --
PUBLIC "ISO/IEC 10744:1997//NOTATION
HyTime Extent List Notation//EN"
-- Attributes [sched]: HyExtLst --
-- CommonAttributes [GenArc]: altreps, included, superdcn --
-- CommonAttributes [base]: bosdatt --
-- CommonAttributes [locs]: egrvplan --
>
<!attlist #NOTATION
HyExtLst -- HyTime Extent List Notation --
-- Clause: 9.4.6 --
GenArc NAME #FIXED GABridN
superdcn NAME #FIXED HyDimLst
>
<!entity % HyDimLst "INCLUDE" >
<!entity % sched "INCLUDE">
]]><!-- HyExtLst -->| Next Clause | Previous Clause |
| Copyright © 1992, 1997 International Organization for Standardization. All rights reserved. This electronic document is for use during development and review of International Standards. Official printed copies of International Standards can be purchased from the ISO and the national standards organization of your country. | |
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