"The problem:"

https://en.wikisource.org/wiki/Page:Railways_Act_1921_(ukpga_19210055_en).pdf/87
https://en.wikisource.org/wiki/Page:Railways_Act_1921_(ukpga_19210055_en).pdf/88
https://en.wikisource.org/wiki/Page:Railways_Act_1921_(ukpga_19210055_en).pdf/89

Contain a table (which is embedded as the parameters supplied to a template to generate a specfic "body" layout arrangement) which continues over many Pages: which are transcluded with Proofread Page/LST

However, they don't currently render correctly on transclusion. Here: https://en.wikisource.org/wiki/Railways_Act_1921#Sch6 is the result..

Currently two templates are used on Wikisource to effect a nominal break in an attempt to "force" the handling. {{nop}} and {{nopt}} . However, it's not from merely looking a those templates which should be used in a given context due to complex interactions of whitespace contributed by, the code in the page, the handling in an intermediate template, the parser, the transclusion method etc..

Expecting a contributor to figure out precise white semantics like this is unreasonable.

"What is the functionality you want?"

An updated table syntax or epxlicitly defined parser tag that will 'enforce' the trimming of whitespace at the end of a previous item, and ensures that a new table row or table item is started cleanly, without having to use the current {{nop}}{nopt}} and other "clever" tactics that cause issues.

I want to be able to write templates that do

{{table start}}
{{body|text={{table rows}}}}
{{footer|{{table end}}}}
.... (Page: break intervenes) ....
{{header|{{table start}}}}
{{body|text={{table rows}}}}
{{body|text={{table end}}}}
{{footer}}

Ideally being able to write or amend my {{table start}},{{table rows}} and {{table end}} template such that they can be "whitespace-independent" whilst remaining compatible with additional template markup that may be present, or writing the entire table directly with HTML5 style table constructs which seems to be incompatible with Mediawiki's general approaches...

Doing this manually at present, is too complicated..

Without having to figure out or worry about complex whitespace interactions!