The clearest example is [p en/ago], which only serves to locate the [ss Time] of some past event in terms of its distance from the present:
- [ex 001 "I arrived a year [p en/ago Time--Interval]. ([ss Time--Interval]) [points backwards from the present: before now]"]
The most common use of [ss Interval] is in the construal [ss Time--Interval]: the time of an event is described via a temporal offset from some other time.
Another retrospective marker, [p en/back], can be transitive [exref 002 Interval], or can be an intransitive modifier of a [ss Time] PP [exref 003 Interval].
Plain [ss Interval] is used in the latter case:
- [ex 002 "I arrived a year [p en/back Time--Interval].[^1] ([ss Time--Interval])"]
- [ex 003 "I arrived [p en/back Interval] in<sub>[ss Time]</sub> June. ([ss Interval])"]
(This category is unusual in primarily marking a construal for a different scene role.
But this seems justified given the restrictive set of English temporal prepositions that can appear with a temporal offset, and the distinct ambiguity of [p en/in].
[ss Interval] is designed as the temporal counterpart of [ss Direction], which can construe static distance measures; in fact, <i>TimeDirection</i> was considered as a possible name, but [ss Interval] seemed more straightforward for the most frequent class of usages.)
Other adpositions can also take an amount of intervening time as their <i>complement</i> (object):
- [ex 004 "I will eat [p en/in] 10 minutes."]
- [‘for no more than 10 minutes’ reading]: [ss Duration][^2]
- [‘10 minutes from now’ reading]: [ss Time--Interval][^3]
- [ex 005 "The game started at 7:00, but I arrived <u>[p en/after Time--Interval]</u>/<u>[p en/within Time--Interval]</u> 20 minutes. ([ss Time--Interval])"]
Some adpositions license a temporal difference measure in <i>modifier</i> position, which does not qualify:
- [ex 006 "To beat the crowds, I will arrive **a while** <u>[p en/before Time] (it starts)</u>/<u>[p en/beforehand Time]</u>. ([ss Time])"]
- [ex 007 "The game started at 7:00, but I arrived **20 minutes** <u>[p en/after Time] (it started)</u>/<u>[p en/afterward Time]</u>. ([ss Time])"]
The preposition [p en/after] can be used either way—contrast [exref 007 Interval] with [exref 005 Interval].
Note that having [ss Interval] as a separate category allows us to distinguish the sense of [p en/in] in [exref 005 Interval] from both the [ss Duration] sense [exref 005 Interval] and the [ss Time] sense (<i>[p en/in] the morning</i>).
## Versus [ss Duration]
The prepositions [p en/in] and [p en/within] are ambiguous between [ss Interval] and [ss Duration].[^4]
The distinction can be subtle and context-dependent.
The key test is whether the phrase answers a <i>When?</i> question.
If so, its scene role is [ss Time]; otherwise, it is a [ss Duration].
- [ss Time--Interval]:
- [ex 008 "I reached the summit [p en/in Time--Interval] 3 days. [= 3 days later, I reached the summit.]"]
- [ex 009 "I was at the summit [p en/within Time--Interval] 3 days. [= 3 days later, I was at the summit.]"]
- [ex 010 "I finished climbing [p en/in Time--Interval] 3 days. [= 3 days later, I finished climbing.]"]
- [ex 011 "They had the engine fixed [p en/in Time--Interval] 3 days. [= 3 days later, they had the engine fixed.]"]
- [ss Duration]:
- [ex 012 "I reached the summit [p en/in Duration] 3 days. [it took not more than 3 days]"]
- [ex 013 "I had climbed 1000 feet [p en/in Duration] [a total of] 3 days."]
- [ex 014 "I fixed the engine [p en/in Duration] 3 days. [it took not more than 3 days]"]
With a negated event, we use [ss Duration]:
- [ex 015 "I haven’t eaten <u>[p en/in Duration]</u>/<u>[p en/for Duration]</u> hours. [hours have passed since the last time I ate] (#When haven’t you eaten?)"]
<!--
Version 1 featured a label called <i>DeicticTime</i>, under <i>RelativeTime</i>, which was meant to cover [p en/ago] and temporal usages of other adpositions (such as [p en/in]) whose reference point is the utterance time or deictic center.
This concept proved difficult to apply and was (without good justification) used as a catch-all for intransitive usages of temporal prepositions.
For v2, the new concept of [ss Interval] is broader in that it drops the deictic requirement (also covering [p en/within]), while [ss Time] has been clarified to include intransitive usages of prepositions like [p en/before] where the reference time can be recovered from discourse context.
-->
[^1]: While <i>a while [p en/back]</i> and <i>a few generations [p en/back]</i> are generally accepted, the use of [p en/back] rather than [p en/ago] for nearer and more precise temporal references, e.g. <i>10 minutes [p en/back]</i>, appears to be especially associated with Indian English ([Yadurajan, 2001](/bib/yadurajan_2001/), p. 7).
[^2]: This usage of [p en/in] has been classified under the terms <i>frame adverbial</i> ([Pustejovsky, 1991](/bib/pustejovsky_1991/)) and <i>span adverbial</i> ([Chang et al., 1998](/bib/chang_et_al_1998/)).
[^3]: This usage of [p en/in], as well as [p en/ago] [exref 001 Interval] and [p en/back] [exref 002 Interval], [exref 003 Interval], are <i>deictic</i>, i.e., they are inherently relative to the speech time or deictic center. (See also ([Klein, 1994](/bib/klein_1994/), pp. 154–157).) This was taken to be a criterion for the v1 category <i>DeicticTime</i>, but that was never well-defined in v1 and was broadened for this version.
[^4]: By contrast, [p en/after] seems to strongly favor [ss Time--Interval]. <i> [pspecial After en/after] a week, I had climbed all the way to the summit</i> is possible, but the conclusion that the climbing took a week may be an inference rather than something that is directly expressed.