title_body: Are there any grammatical aspects which do not have parallels in natural languages? In Describing Morphosyntax, Payne uses a number of diagrams for visually explaining aspects and what they say about actions relative to time.
  
  Payne outlines the following, all of which occur in natural languages.
  
  Perfective
  
  [-----] He wrote a letter.
  
  Imperfective
  
  &lt;-----&gt; He writes letters.
  
  Perfect
  
  -----|x He has come from Aqaba.
  
  Pluperfect
  
  ---|DC---(now) I had entered a congested zone.
  
  Completive
  
  &gt;-----| She finished working.
  
  Inceptive
  
  [-----&gt; She began working.
  
  Continuative/progressive
  
  &gt;-----&gt; He is writing letters
  
  Punctual
  
  x He sneezed.
  
  Iterative
  
  &gt;-x-x-x-&gt; He is coughing.
  
  Habitual
  
  &lt;-----&gt; He drinks.
  
  
  
  Are there other Aspects that do not appear in natural languages which have been invented for conlangs, and could they be represented with a similar visual diagram?
upvoted_answer: Well, y'know, ANADEW and all that, but...
  
  As far as I know, there is no natural language with a grammaticalized antiperfect aspect--i.e., an aspect where the time of the action is after the reference point, rather than before.
  
  Present Perfect: "He has come."
  Past Perfect (pluperfect): "He had come."
  Future Perfect: "He will have come."
  
  In each case, the event occurs before the reference time defined by the tense. In the case of future perfect, this may or may not be before the present.
  
  An antiperfect flips that around
  
  Present Antiperfect: "He is going to come." / "He is about to come."
   (approximately)
  Past Antiperfect: "He was going to come." / "He was about to come."
   (approximately)
  Future Antiperfect: "He will be going to come." / "He will be about to come." (approximately)
  
  The various English paraphrases all have some extraneous additional implications (e.g., "He was going to come" implies that he didn't actually, "about to" implies that the action is nearby) that are not inherent to the antiperfect aspect, if it were grammaticalized. The important thing is that the action occurs after the reference time, but not necessarily after the present. Thus, just like a future perfect action could have occurred in the past, a past antiperfect could occur in the future.