A chapter from Practical Hypermedia: An Introduction to HyTime, by W. Eliot Kimber
This appendix summarizes the changes made to the first edition of the HyTime standard by the publication of second edition of the HyTime standard, ISO/IEC 10744:1997 in August 1997. These changes are grouped into four categories: syntax changes, new facilities, new architectural forms, and new and changed data content notations.
all-actattribute list form is now the
activityattribute list form. The
activityattribute is replaced by the
actrulesattribute, which points to the activity policy association rules (
actrule) that govern the element. See "6.7.3 Activity policy association ".
all-idattribute list has been redistributed as follows:
conlocattribute (part of the original
all-idattribute list), has been superceded by the more general value reference facility. The original
conlocattribute is now simply an application of the value reference facility (see " 6.7.1, Value Reference").
opacityattribute, one of the general attributes of the General Architecture.
HyNamesattribute is now defined via the normal architecture use declaration mechanisms defined in the AFDR facility of the SGML Extended Facilities (see " A.3"). The name "HyNames" is no longer required by the HyTime architecture as documents are free to use any names they want when configuring the use of an architecture.
idattribute is now part of the common attributes for elements of the General Architecture (see "A.5.2, Common attributes of elements ").
notationattribute is eliminated. The use of data content notations with elements can now be controlled using the Data Attributes for Elements (DAFE) facility of the General Architecture (see "A.5.3").
activityelement form is replaced by the
actrule(activity policy association rule) element form. An activity rule associates elements with the policy specifications that govern their access according specified activity types. The HyTime architecture no longer defines a fixed set of activity types, although it does define a starter set.
all-lexattribute list form has been replaced by the Lexical Type Definition Requirements facility of the SGML Extended Facilities, see "Annex A.2" for details.
batonelement form can now include
progrpelements, in addition to
all-refattributes have been split beween the immediate reference type control facility of the General Architecture and the reference control facility of the HyTime location address module. See "A.5.5, ID immediate referent type control" and "7.7, Reference control".
evschedsattribute with the new
schedsattribute and the original
pevschedattribute with the new
targschd(target schedules) attribute.
biblocform now takes the unique
bibsrc(bibliographic location source) attribute, which points to another bibliographic location that defines the addressing context for the first
calendarattribute list has been superceded and replaced by more complete calibration and calendar specification facilities. See "9.9, Calibrated real time axes".
clinkform is now formally derived from the new
hylinkform. This means that
clinkcan take all of
hylink's attributes (except
anchrole, which is fixed for
clinkin the HyTime architecture).
degradeattributes have been removed. They are replaced by the more general facilities for formal system identifiers (FSI), part of the SGML Extended facilities (see "A.6 Formal System Identifier Requirements"), by which any of these attributes can be defined for specific storage managers. The attributes
superdcnare now defined by the General Architecture, which is part of the SGML Extended Facilities (see "A.5"). The
encodingattribute is now defined by the FSI facility.
dimlistelement form has been replaced by the
%dimlistparameter entity, which expands to all the possible ways in which dimension specification lists can be represented.
dimrefelement form has been redefined and enhanced to reflect the new, more generalized event schedule and finite coordinate space model. In particular, it makes it possible to distinguish references to modified and unmodified (by rendition processing) extents.
markfun(marker function) element form. As a marker function, dimension specifications can use any marker function notation, with the default being the HyTime marker list notation.
datalochas been generalized into a general facility for defining data tokenizers and data parsers and parsing contexts. The
datalocelement form is now a combination of a list location address with a data tokenizer grove constructor (
dvlist) element form has a new attribute,
defatts(default-setting attributes). This attribute names attributes whose values become the new default values for attributes controlled by the default value list. This enables the definition of the propagation rules for attribute values in combination with the use of default value lists to set the initial values of implied attributes. This provides what is essentially #CURRENT behavior for attributes, but down the element tree, rather than sequentially through the document.
object) to address the objects that they schedule as an alternative to containing them syntactically. The accessed anchor list mechanism has been replaced by the more general element forms hyperlink location address (
linkloc) and hyperlink anchor location address (
anchloc). The new attribute
align(object alignment) specifies how the object is to be aligned within the extent of the event.
grpscopeattribute, which has been superceded by more complete event grouping and control mechanisms.
fcselement form has been redefined. Axes are now defined using attributes of the
fcselement, rather than subelements. The original
axisdefsattribute has been replaced by the
axesattribute, which specifies the names of the attributes of the same element that define the axes of the coordinate space.
The association of FCSes with measurement domains and units has been extended and generalized, including the addition of the ability to calibrate axes according to some real measurement system or event (e.g., you can associate the start of a time axis with a precise point in real time).
You can now use
fcs elements by reference from event schedules, in addition to
having them contain event schedules directly, as was required in HyTime First
fcslocform can be achieved by defining a notation-specific query notation and using it with a query location address element. The new and improved
fcslocaddresses scheduled objects by addressing the region of the coordinate space within which they are scheduled. In essence, the
fcslocprovides a marquee selection (bounding box) mechanism for addressing scheduled objects. This lets you address whatever objects happen to fall within a particular portion of a coordinate space (for example, at a particular time or time span along a time axis).
gdattribute has been replaced by the granule definition notation (
gdnot) attribute. Granules can be defined using any notation.
unmspaceattribute has been removed as the concept of unified name spaces has been replaced by the more general mechanism for defining name spaces with groves. The
docdmuattribute has been replaced by new facilities for defining finite coordinate spaces (see "9, scheduling module").
ilinkform, two new hyperlink forms have been added,
varlink(variable link). These three forms provide the three possible syntax configurations for addressing anchors.
hylinkuses one attribute per anchor role while
varlinkuses one subelement (
anchspec) to address the members of each anchor.
ilinkstill uses the single
linkendsattribute to address the anchors of the link.
aggtrav attributes have been eliminated. The HyTime
architecture no longer has an opinion on the issue of anchor description and
the whole concept of aggregate locations has been replaced by the grove addressing
model and the new
form (which is derived from
The hyperlink traversal rule attributes
extra have been replaced by a single attribute,
linktrav. In addition, traversal among
the members of an anchor is controlled with the new attribute,
cantcnstdefines the behavior when a grove cannot be constructed from the location source.
The location source can be omitted for any location
address that is not an intermediate rung in a location ladder. For all location
address forms except
nameloc (which don't take the
attribute), when the
locsrc attribute is omitted, the
location source is defined according to the settings of the implied location
source attributes (
default, the implicit location source is the non-location-address element
that directly or indirectly addresses the location ladder of which the location
address is the top (or only) rung.
marklistelement form has been replaced by the
%marklistparameter entity, which expands to all the possible ways in which marker lists can be represented.
agglochas been eliminated from the
multlocattribute list. The concept of aggregate locations has been replaced by a clearer definition of multi-object anchors and by the
namelocform is now formally derived from the new
mixedlocelement form, which has the semantic of addressing whatever the location address elements in its content address.
nmlistelement form is now formally derived from the new
nmsploc(name space location address) element form. The
nmsplocform provides the ability to address nodes in any named node list in any grove.
dtdorlpd attributes have been eliminated.
The function of
obnames has been subsumed by the implications
of grove-based addressing and the general semantics of location addresses.
dtdorlpd attribute has been replaced by the
active data attribute defined by the SGML
notation, which is defined as part of the definition of the SGML property
set (see "A.7, SGML property set").
querylocelement form. It maintains the original
qdomainattribute from the original
queryattribute list but it's now simply a renaming of the normal
locsrcattribute. It also takes the new attribute
notfound, which indicates the behavior when the query fails to find any nodes.
proploc(property location address) form has been updated to reflect the new grove model. It now addresses the value of the property of a node in a grove by property name. The attribute
jointis no longer relevant and has been eliminated. A new attribute,
direct, lets you address either the direct value of a property or the effective value resulting from the application of the value reference facility (see "Value Reference").
apporderis eleminated as the ordering of rendition rules is inherent in their grove representation.
relloc) element form has been refined. The original attribute
roothas been replaced by the normal meaning of the location source attributes (in particular, the new implied location source facility means that an omitted location source is, by default, the root of the primary tree, which is what the
rootattribute meant). The new attribute starting node (
strtnode) addresses the node whose relatives are being addressed.
fcs(governing finite coordinate space),
coverage(extent coverage), and
overlap(is overlap allowed?). The attribute
apporderis eleminated as the ordering of events is inherent in their grove representation.
spanlocattribute of the
spanlocattribute list has been redefined to remove the
spanlinkkeyword. Span addressing has been formalized and clarified as well.
wandelement form can now include
modgrpelements, in addition to
abstimeelement form has been superceded and replaced by more complete calibration and calendar specification facilities. See "9.9, Calibrated real time axes".
linkloc) and hyperlink anchor location address (
anchloc). These location addresses can be used with events to associate an event with a link or one of its anchors. Specific applications could also define more specialized queries for expressing the semantic relationship between events and hyperlinks and their anchors (or any other addressible object for that matter).
axiselement form has been eliminated. The axes of finite coordinate spaces are now defined directly by attributes of the
dateelement form has been superceded and replaced by more complete calibration and calendar specification facilities. See "9.9, Calibrated real time axes".
docmduattribute has been eliminated as it is replaced by facilities of the redesigned finite coordinate space mechanism.
repscopeattribute for controlling the repetition of an event group.
juldateelement form has been superceded and replaced by more complete calibration and calendar specification facilities. See "9.9, Calibrated real time axes".
lexmodelform has been replaced by the more general Lexical Type Definition facility (see "A.2, Lexical Type Definition Requirements (LTDR) ").
lexordform has been replaced by the more general Lexical Type Definition facility (see "A.2, Lexical Type Definition Requirements (LTDR) ").
queryloc(query location address) element form. The difference between these two is that the results of a notation-specific location address were undefined, while the results of a query location address must be nodes in a grove. However, a query location address can still use any query notation.
queryloc(query location address) element form. The original
qcontextattributes are replaced by the general facilities for defining and addressing location sources.
scalerefelement form has been superceded and replaced by more complete projection specification facilities. See "10.3, Projection".
timeoffelement form has been superceded and replaced by more complete calibration and calendar specification facilities. See "9.9, Calibrated real time axes".
The mechanism for declaring the use of the HyTime architecture and specifying the modules and features needed by a document has been changed to reflect the new enabling architecture facility defined in "A.3, Architectural Form Definition Requirements (AFDR) ", part of the SGML Extended Facilities. In general, the use of processing instructions has been replaced by the use of data content notation declarations and data attributes, except for the architecture use declaration processing instruction, provided by Ammendment 1 to ISO/IEC 10744:1997.
A new set of facilities, the SGML Extended Facilities have been defined. The SGML Extended Facilities provide functions that the HyTime architecture needs but that are general to all SGML applications, not just hypermedia. The new facilities are:
lextypeattributes from the base module.
The architectures defined in ISO/IEC 10744:1997 and ISO/IEC 10179 (DSSSL) conform to this clause.
The reference location address facility of the location address module
enables the direct use of any addressing method from attributes of elements,
rather than using indirect addressing. This includes the ability to use query
location addresses. This means you can use any form of query directly from
elements in a way that is meaningful and well defined in a larger HyTime framework.
This enables, for example, the declaration of the HTML
element as a conforming HyTime contextual link. See "7.8, Reference location address".
The implied location source facility allows you to create indirect location addresses that do not address their location sources explicitly. This enables, for example, location addresses that are relative to the non-location-address elements that use them. It can greatly simplify the syntax of location addresses. See "7.3, Implied location source".
The calibration facility of the scheduling module makes it possible to calibrate time axes of finite coordinate spaces in terms of real measurements, such as real time. This facility replaces and generalizes the original calendar specification facility. See "9.3.1, Axis calibration", and "9.9, Calibrated real time axes".
agglinkform, along with a clearer definition of multi-object anchors, replaces the original aggregate link concept. Any existing
namelocelement that used the
agglocattribute can be redefined as an
agglinkwithout modifying element instances.
inbos), what it's processing priority is (
bosprrty), and whether or not it's a sub hub document (
bosspecattribute for the HyTime document element. The
bosspecattribute points to
bosspecelements in the same document that modify the inclusion or exclusion of entities in the HyTime BOS.
datatokelement form is the data tokenizer grove constructor. It can be used to define data tokenizer groves not provided by the
datalocelement form (which combines a data tokenizer with a list location).
ilinkform in that it uses separate attributes to address the anchors of the link, one for each anchor. The original
agglinkforms are derived from the
mixedlocform is the base from which the
namelocform is derived.
notloc(notation-specific location address) form. Query location addresses differ from notation-specific location addresses in that the results of resolving a
querylocquery must be nodes in a grove. This makes all HyTime location addressing closed over nodes in groves while enabling the clean and clear integration of any addressing method into a HyTime framework.
ilinkby using subelements to define and address each anchor, rather than using attributes of the link element. It does not require that the anchor roles be fixed within a link type. The XML Link
extendedelement form can be derived from the
datalocelement form is defined.
anchloclocation address element form.
linkloclocation address element form.
HTML generated from the original SGML by Jade DSSSL Engine using style specification created by the author.