chris-littlePC1.6 editorial changes addressed

23-049/sections/00-preface.adoc

@@ -5,16 +5,16 @@ When OGC standards involve time, they generally refer to the ISO documents such
 
 Much effort over decades has gone into establishing complex structures to represent calendar based time, such as the <<iso8601>> notation, and many date-time schemas. A consequence of this effort is that many end-users and developers of software use calendar based "coordinates", with the associated ambiguities about underlying algorithms, imprecision and inappropriate scope.
 
-The aim of this Abstract Specification is to establish clear concepts and terminology, so that people are well aware of the advantages and disadvantages of adopting a particular technological approach and then perhaps contribute to building better interoperable systems.
+The aim of this Abstract Specification is to establish clear concepts and terminology, so that people are well aware of the advantages and disadvantages of adopting a particular technological approach to time and then perhaps build better, more appropriate, interoperable systems for their use cases.
 
 [abstract]
 == Abstract
 
 The primary goal of the Abstract Conceptual Model for Time is to establish clear concepts, their relationships, and terminology.
 
-Traditionally, geospatial communities used 2D coordinates and the vertical (third dimension) and temporal aspects were considered attributes rather than valid components of coordinate systems. In an increasingly dynamic, faster and multidimensional world, much confusion and lack of interoperability has occurred because of inconsistent approaches to defining and expressing time. Various international bodies expended considerable effort to establish the Gregorian Calendar as a consistent timeline. The Gregorian Calendar suffices for low precision applications, such as to the nearest minute, but not so when second or sub-second accuracy is required. For example, there has been differing practices and no consensus on whether leap seconds should be part of the Gregorian timeline.
+The fundamental concepts of events, clocks, timescales, coordinates and calendars have been long established, but there is no clear, straightforward defining document. This Abstract Specification provides clear consistent definitions of the fundamental concepts and terminology. The conceptual model enables advantages and disadvantages of adopting a particular technological approach to be identified and provides an opportunity for communities to build consistent, interoperable representations regardless of implementation.
 
-The fundamental concepts of events, clocks, timescales, coordinates and calendars have been long established, but there is no clear, straightforward defining document. This Abstract Specification provides clear consistent definitions of the fundamental concepts and terminology. The conceptual model enables advantages and disadvantages of adopting a particular technological approach to be identified so that the community can contribute to building better and more interoperable systems by defining more detailed documents such as logical and implementation standards that have an agreed common conceptual basis and terminology.
+Traditionally, geospatial communities used 2D coordinates and the vertical (third dimension) and temporal aspects were considered attributes rather than valid components of coordinate systems. In an increasingly dynamic, faster and multidimensional world, much confusion and lack of interoperability has occurred because of inconsistent approaches to defining and expressing time. Various international bodies expended considerable effort to establish the Gregorian Calendar as a consistent timeline. The Gregorian Calendar suffices for low precision applications, such as to the nearest minute, but not so when second or sub-second accuracy is required. For example, there have been differing practices and no consensus on whether leap seconds should be part of the Gregorian timeline.
 
 This document is consistent with <<iso19111>> and <<w3cowltime,W3C Time Ontology>> in OWL.
 

23-049/sections/03-references.adoc

@@ -4,7 +4,7 @@
 
 * [[[rfc3339,IETF RFC 3339]]]
 
-* [[[iso8601,ISO 8601:2004]]] ISO: _ISO 8601:2004, Information interchange Representation of dates and times_. International Organization for Standardization, Geneva (2004). https://www.iso.org/standard/40874.html[https://www.iso.org/standard/40874.html].
+* [[[iso8601,ISO 8601]]] ISO: _ISO 8601, Information interchange Representation of dates and times_. International Organization for Standardization, Geneva. https://www.iso.org/standard/40874.html[https://www.iso.org/standard/40874.html].
 
 * [[[iso19111,ISO 19111:2019]]] ISO: _ISO 19111:2019, Geographic information - Referencing by coordinates_. International Organization for Standardization, Geneva (2019). https://www.iso.org/standard/74039.html[https://www.iso.org/standard/74039.html].
 

23-049/sections/08-temporal-regimes.adoc

@@ -4,7 +4,7 @@
 
 To enable more clear reasoning about time, this Abstract Specification uses the term “Regime” to describe the fundamentally different types of time and its measurement. This is a pragmatic approach that allows the grouping of recommendations and best practices in a practical way, but without obscuring the connection to the underlying theoretical components.
 
-The first three regimes, described below, have deep underlying physical and mathematical foundations which cannot be legislated away. The fourth regime, calendars, uses a seemingly random mixture of ad hoc algorithms, arithmetic, numerology and measurements. Paradoxically, the calendar regime has historically driven advances in mathematics and physics. See the article <<scientificamerican,A Chronicle Of Timekeeping>>.
+The first three regimes, described below, have deep underlying physical and mathematical foundations which cannot be legislated away. The fourth regime, calendars, concerns social constructs using seemingly random mixtures of ad hoc algorithms, arithmetic, numerology and measurements. Paradoxically, the calendar regime has historically driven advances in mathematics and physics. See the article <<scientificamerican,A Chronicle Of Timekeeping>>.
 
 With due consideration, the regimes are applicable to other planets and outer space.
 
@@ -16,7 +16,7 @@ In this regime, no clocks or time measurements are defined, only events, that ar
 
 One set of events may be completely ordered with respect to each other, but another set of similar internally consistent ordered events cannot be cross-referenced to each other unless extra information is available. Even then, only partial orderings may be possible.
 
-In this regime, the <<temporal_knowledge,Allen Operators>> (see <<fig-interval-relations>>) can be used. If A occurs before B and B occurs before C, then that A occurs before C can be correctly deduced. The full set of operators also covers pairs of intervals. So in our example, B occurs in the interval (A,C). However, arithmetic operations like (B-A) or (C-A) cannot be performed as any timescale or measurements are not defined. For example, in geology, 'subtracting' Ordovician from Jurassic is meaningless. In archeology, 'subtracting' a layer with a certain type of pottery remains from the layer containing burnt wood and bones is again not meaningful. Only the ordering can be deduced.
+In this regime, the <<temporal_knowledge,Allen Operators>> (see <<fig-interval-relations>>) can be used. If A occurs before B and B occurs before C, then it can be correctly deduced that A occurs before C. The full set of operators also covers pairs of intervals. So in our example, B occurs in the interval (A,C). However, arithmetic operations like (B-A) or (C-A) cannot be performed as any timescale or measurements are not defined. For example, in geology, 'subtracting' Ordovician from Jurassic is meaningless. In archeology, 'subtracting' a layer with a certain type of pottery remains from the layer containing burnt wood and bones is again not meaningful. Only the ordering can be deduced.
 
 This regime constitutes an Ordinal Temporal Reference System, with discrete enumerated ordered events.
 
@@ -37,7 +37,7 @@ It may seem that time can be measured between 'ticks' by interpolation, but this
 
 The internationally agreed atomic time, TAI, is an example of a timescale with an integer count as the measure of time. However in practice, TAI is an arithmetic compromise across about two hundred separate atomic clocks, corrected for differing altitudes and temperatures.
 
-In this regime, <<temporal_knowledge,Allen Operators>> (see <<fig-interval-relations>>) also can be used. If L occurs before M and M occurs before N, that L occurs before N can be correctly deduced. The full set of operators also covers pairs of intervals. So if M occurs in the interval (L,N),  integer arithmetic operations such as (M-L) or (N-L) can be performed. This is because an integer timescale or measurement is defined.
+In this regime, <<temporal_knowledge,Allen Operators>> (see <<fig-interval-relations>>) also can be used. If L occurs before M and M occurs before N, it can be correctly deduced that L occurs before N. The full set of operators also covers pairs of intervals. So if M occurs in the interval (L,N),  integer arithmetic operations such as (M-L) or (N-L) can be performed. This is because an integer timescale or measurement is defined.
 
 This regime constitutes a Temporal Coordinate Reference System, with discrete integer units of measure which can be subject to integer arithmetic.
 
@@ -51,7 +51,7 @@ It is also assumed that time can be extrapolated to before the time when the clo
 
 This gives us a continuous number line to perform theoretical measurements. This is a coordinate system. With a datum/origin/epoch, a unit of measure (a name for the 'tick marks' on the axis), positive and negative directions and the full range of normal arithmetic. This is a Coordinate Reference System (CRS).
 
-In this regime, the <<temporal-knowledge,Allen Operators>> (see <<fig-interval-relations>>) also can be used. If A occurs before B and B occurs before C, that A occurs before C can be correctly deduced. The full set of operators also covers pairs of intervals. So if B occurs in the interval (A,C), real number arithmetic operations like (B-A) or (C-A) can be performed. This is because a timescale or measurement has been defined, and between any two instants, an infinite number of other instants can be found.
+In this regime, the <<temporal-knowledge,Allen Operators>> (see <<fig-interval-relations>>) also can be used. If A occurs before B and B occurs before C, it can be correctly deduced that A occurs before C. The full set of operators also covers pairs of intervals. So if B occurs in the interval (A,C), real number arithmetic operations like (B-A) or (C-A) can be performed. This is because a timescale or measurement has been defined, and between any two instants, an infinite number of other instants can be found.
 
 [example]
 ====
@@ -80,14 +80,18 @@ A Calendar is a Temporal Reference System, but it is not a Temporal Coordinate R
 
 There are other regimes, which are out of scope of this Abstract Specification. This could include local solar time, which is useful, for example, for the calculation of illumination levels and the length of shadows on aerial photography, or relativistic time.
 
-==== Local Solar Time
+==== Accountancy
 
-Local solar time may or may not correspond to the local statutory or legal time in a country. Local solar time can be construed as a clock and timescale, with an angular measure of the apparent position of the sun along the ecliptic (path through the sky) as the basic physical principle. But the sun does not appear to progress evenly along the ecliptic throughout the days and year. There may be variations of up to 15 minutes compared to an even angular speed.
+The financial and administrative domains often use weeks, quarters, and other calendrical measures. These may be convenient for the requisite tasks, but are usually inappropriate for scientific or technical purposes.
 
 ==== Astronomical Time
 
 Astronomers have traditionally measured the apparent locations of stars, planets and other heavenly bodies by measuring angular separations from reference points or lines and the timing of transits across a meridian. Generally astronomers use time determined by earth's motion relative to the distant stars rather than the sun. This is called sidereal time. Times are usually measured from an epoch in daylight, such as local midday, rather than midnight. Accurate measurements of positions of stars, planets and moons were and are essential for navigation on Earth. See the book <<astro_algo,Astronomical Algorithms>> by Jean Meeus for examples of the calculations involved.
 
+==== Local Solar Time
+
+Local solar time may or may not correspond to the local statutory or legal time in a country. Local solar time can be construed as a clock and timescale, with an angular measure of the apparent position of the sun along the ecliptic (path through the sky) as the basic physical principle. But the sun does not appear to progress evenly along the ecliptic throughout the days and year. There may be variations of up to 15 minutes compared to an even angular speed.
+
 ==== Space-time
 
 When dealing with moving objects, the location of the object in space depends on its location in time. That is to say, location is an event in space and time.
@@ -108,7 +112,5 @@ Relativistic effects may need to be considered for satellites and other spacecra
 
 The presence of gravitational effects requires special relativity to be replaced by general relativity, and it can no longer be assumed that space (or space-time) is Euclidean. That is, Pythagoras' Theorem does not hold except locally over small areas. This is somewhat familiar territory for geospatial experts.
 
-==== Accountancy
 
-The financial and administrative domains often use weeks, quarters, and other calendrical measures. These may be convenient (though often not!) for the requisite tasks, but are usually inappropriate for scientific or technical purposes.