EPUB 3 Working Group Virtual Locators Task Force Telco — Minutes

Date: 2021-08-20

See also the Agenda and the IRC Log


Present: Wendy Reid, Ivan Herman, Avneesh Singh, Brady Duga, Hadrien Gardeur, Will Awad, Dan Lazin, Tzviya Siegman



Chair: Wendy Reid

Scribe(s): Brady Duga, Wendy Reid


Wendy Reid: https://docs.google.com/document/d/11GypOjE9xOTaINATl5bxVIA3Mc9jzNBGCr6GT_KNaQ4/edit

Wendy Reid: Sorry for missing the last meeting

Dan Lazin: Most people that are here today weren’t at the last meeting

1. document review

Wendy Reid: Added a better definition of page list

Dan Lazin: Repost for those who missed the link: https://docs.google.com/document/d/11GypOjE9xOTaINATl5bxVIA3Mc9jzNBGCr6GT_KNaQ4/edit#heading=h.gbsmtjlkuon

Wendy Reid: [Reviewing comment in the doc]

Hadrien Gardeur: Is the page size calculated or authored?
… if it is calculated than fine, we can use characters
… but if it is authored then there can’t be a fixed rule
… calculated vs authored is an important distinction

Wendy Reid: The guiding principle is authors should provide their own list, but in the absence of that we have a calculated alternative

Hadrien Gardeur: If we follow the terminology then page list should only refer to the authored content
… so this definition is confusing

Wendy Reid: Agreed. Maybe just remove the fixed size reference here

Hadrien Gardeur: I am concerned about using the same term (“page”) for two different things
… they are used in similar ways, but they aren’t really the same, so using the same term is confusing

Dan Lazin: So are you saying page is ok in the UI, but we should have different terms for authored page list page and the calculated page

Avneesh Singh: Would be good to have different terms

Hadrien Gardeur: We can look at existing implementations and see what terms have been used
… In readium they are called positions
… can have multiple positions on the page
… used for a lot of things

Brady Duga: We also have positions, and does the same thing. We don’t use it when the page list is missing
… one issue is a page list, but you can also have a list of positions
… the way we handle a missing page list is to create a fake one
… it’s based on the RMSDK
… we would create a not-great page list that would be consistent but not as good as an authored oen

Hadrien Gardeur: Calculated positions are in memory and not persisted
… But may persist for annotations
… I imagine page and position are complementary and both exist for different purposes
… One is a non-exhaustive string, the other is exhaustive (no gaps)
… There will be different use cases

Wendy Reid: Working on this terminology is important, given the discussion
… Kobo uses position markers, but it is not at all related to page lists
… Kobo is a locator, need a term for a calculated page

Ivan Herman: Is the difference calculated or not?
… Annotations, etc, are dynamic and to me that is a position
… And the other is from the author and is set statically

Wendy Reid: Summarizing. There is page and calculated page, but we want a better name

Tzviya Siegman: What about calculated page?

Hadrien Gardeur: Reviewing the doc at trying to decide if we are creating page lists or position lists
… Some use case want page, but others work better with positions
… So the answer to the question of what we really want to make isn’t clear
… it looks like we want both
… For some, dealing with strings, it will be hard to implement a UI

Wendy Reid: We don’t consider UI much, we probably should consider it

Tzviya Siegman: For some it won’t matter if it is calculated or not, just so long as they are the same
… The UI is an important point and is an issue we have had in the past with calculated pagination
… Images are particularly a problem

Hadrien Gardeur: For use case 1, if there is a string and kids need to enter it they will make mistakes
… due to typos, etc
… For the second case, it does matter if it is authored or calculated
… since you need a reference that works across print and epub

Wendy Reid: Authored and calculated will the terms and I will make an attempt at defining them
… Maybe review the use cases as homework
… And think about the desired end product
… Any thoughts?

crickets: chirp

Dan Lazin: Should note that a calculated page won’t exist if there is an authored page (mutually exclusive)

Wendy Reid: Maybe expand the section on persistence

Dan Lazin: I just added that

Tzviya Siegman: Can we add images, math, etc into the process

Hadrien Gardeur: If you are using bytes then mathml just works by magic
… Depends on what you are counting
… images less so
… requires rendering first

Ivan Herman: Going back to what Brady said, the calculated page list is “bad” and is meant as a stick to convince authors to include them
… So maybe we shouldn’t spend too much time worrying about the perfect algorithm
… This is an absolute fallback

Hadrien Gardeur: There is quite a bit of complexity to manage the algorithm
… When making the list you will likely have different information available than when you are actually displaying the page

all: general discussion of how hard it is to figure out the size of markup

Dan Lazin: Added a section to the doc just now to cover this

Ivan Herman: What we are talking about here is for the static page list
… It is not for annotations, etc. Is that correct?

Hadrien Gardeur: You could enhance an annotation with that information
… the simplest thing you can do for annotations is the original text
… Then you can add position information to annotation like how far in the doc it is
… which is good for anchoring

Ivan Herman: I think that backs my claim, there are distinct things here
… the static and dynamic are both useful

Hadrien Gardeur: The one thing all reading systems need is the position list
… Why do you need to calculated a page list for any use case
… Why does GPB calculate the page list?