For all the Authors out there. The semantics of telling a time travel story is really not that hard or confusing. If I may, here are some insights of mine.
We already have all the necessary words to describe non linear temporal phenomenon (e.g. time travel, faster than light travel, relativistic velocity travel, etc) and their associated side effects; we've developed them to deal with Einstein's Theory of General Relativity.
A very important concept to 'grok' is Frame of Reference. A Frame of Reference is any 'space' that is undergoing uniform acceleration; of which there are generally two types: gravity wells and vehicles underway at 'escape velocity' or greater.
Temporal description falls into three broad categories: point in time descriptions, objective time duration descriptions, and subjective time duration descriptions.
Point in time descriptions are self explanatory. The traditional use of 'calendar' dates and times o'the-clock are sufficient. Keep in mind, the calendar & clock are only valid in that Frame of Reference. For example, the pre-spaceflight calendars developed by mankind are, in essence, interchangeable but none of them are valid anywhere other than Earth. Calendars (and clocks) are synchronized by the use of 'epochs' (correlated point in times on different calendars). In the next paragraph I'll give a real world example of what I mean.
The Gregorian Calendar is in common use on Earth but something had to be developed for long duration Mars landing missions. After the landings, calendars (and clocks) were used by mission personnel that relied on a Martian Day (called a Sol) so that they would work in shifts related to the landers. The calendars and clocks were synchronized at the epoch of the landing. There are currently several candidates to become 'official' Martian calendars (and clocks), some using the 'Telescopic Epoch' (a point in time in 1609 Gregorian Calendar that recognizes the earliest telescopic observations of Mars).
The concept of a calendar & clock for a FoR applies to spaceships too. We just need to go back to the Age of Sail to understand it. The Captain's Log kept track of the events of the voyage based upon the clock it carried (for elapse times) and the observations of the 'heavens' (which established reliable epochs). So, story-wise, Roddenberry et al got it right with "Captain's log, stardate ~~~ ...". Mind you, the shipboard calendar & clock is distinct and unique for each ship per mission (cruise, deployment, dispatch, or whatever). Departure and arrival signaling at a 'port of call' (or any way-point with its own FoR) generate epochs; as do exo-ephemerides (calculated positions of astronomical or cosmological objects external to the FoR) observations.
The application of calendars & clocks within compound gravity wells has its own wrinkles. Compound gravity wells are systems with zero or more focal bodies and one or more satellite bodies where each body is planetoid (of dwarf planet mass) or better; where the focal bodies provide the composite gravity field for the FoR; and where each focal or satellite body in the system is its own FoR. Examples of compound gravity wells are: multi-body planetary systems such as the Earth-Luna system or the Jovian system, stellar systems, stellar clusters (actual based on gravitic interaction as oppose to apparent based on angle of observation), and galaxies. The overall calendar & clock for the compound well does not apply to the subordinate gravity wells; it only applies within the superordinate gravity well, in-between the subordinate gravity wells. The overall calendar & clock can be used for bridging structure for synchronizing the individual calendars & clocks of the subordinate FoRs. Although exo-ephemerides observations can be used to generate epochs, intra-ephemerides observations along with focal body(ies) pattern(s) observations are the most likely way to generate epochs related to the superordinate FoR.
An example of point in time descriptions using calendars & epoch: The captain of the interplanetary cruise ship "The Tara of Helium" en-route to the Port of Phobos outbound from the Peruvian High Station reports the near miss of a dark asteroid on Day 43 13:47 shipboard time. The captain, as mandated, includes a sun spot pattern picture to timestamp the event and forwards the report to both the previous and the next ports of call. The space-ways manager at each port, via the included timestamp, renders the report: into solar date-time for warning alerts for potentially affected traffic and into local date-time for report logging.
On to objective and subjective time durations.
Objective time duration is the measurement from one point in time to another, with respect to the same FoR. Subjective time duration is the measurement from a point in time with respect to a person or thing that travels between FoRs to another point in time for the same person or thing. Objective time relates to subjective time like weight relates to mass. Another way to look at it is: objective time duration is the summation of moments that have occurred with the FoR between two points in time (on the timeline associated with the FoR); whereas, subjective time duration is the summation of moments that have been experienced by the person or thing between two points in time (on their timeline). Objective time can best be described by words indicating the passage/metering of time, while subjective time can best be described by words indicative of age/ageing (where age can be considered the amassing/accumulation of experiences).
In regards to the concept of past and future: if it's absolute or impersonal then it's objective time - that occurred in the past - implies an event in this FoR that occurred prior to now; if it's possessive then it's subjective time - that occurred in my past - implies an experience along my timeline/lifeline that occurred prior to now. For subjective time: younger times is synonymous with past (or earlier) times; while older times is synonymous with future (or later) times. An example of incorrect phrasing: "In the past I went to the future"; correct phrasing: "In my past I went to the future".
Subjective time always has a starting point in time when/where the sum of experiences is zero. Subjective time also has an implicit (sometimes explicit) ending point in time when/where the subject is no longer capable of accumulating experiences in the form that it started out as. These points of times are epochs.
Objective time can be 'converted' to subjective time by making the subject the FoR and identifying the starting epoch; geological periods are an example of this. Objective time for a vehicular FoR is, by definition, also subjective time.
I'll end my suggestions here. Hope this helps a bit.
This is the preface to my story My Three Divas - an eros opera : The Interregnum.
This series was inspired by 'Dating Maggie' by SpacerX. A few years back SpacerX took a hiatus from his epic 'Dating Maggie' (to deal with his other epic 'Six Times a Day'). At that time I was so enthralled with his work that I wrote some fan fiction to continue his story a bit. For various reasons I did not continue with that fan fiction extension but the premise and the main characters stayed with me, haunted me. So after a time and some work I refashioned it to make them mine. 'My Three Divas' is not a retelling of 'Dating Maggie', it is a different story that shares the same premise and a similar starting point.
Thank you SpacerX for the epic works that you have done. Thank you for the inspiration that you and your work enabled. I hope you like what I've done with your clay.
This novelette is the gateway into the My Three Divas series. A chronicle of the beginning is already in the works, with other prequel chronicles planned; sequel chronicles are being considered, but it depends on how much the ménage de quatre & their cohort wants to tell.
I hope you enjoy Jean-Henri, Lisa, Holly, Niharika, et al as much as I enjoy writing about them.
Got to go - the Divas are demanding my attention!
Ciao
Da T. Angel