What Plain Text is
Plain text here means columns lined up with spaces, the way a command line tool prints a table.
Terminal output, log files, fixed-width exports from older systems.
What Jira is
Jira wiki markup uses double pipes for header cells and single pipes for data cells.
Jira issues, comments and descriptions.
What changes when you convert Plain Text to Jira
Two shapes are handled. If the same character positions are blank on every line, those gutters are treated as column boundaries, so values containing single spaces stay intact. Otherwise the lines are split on runs of whitespace.
Empty cells are filled with a single space, because a Jira row with two adjacent pipes collapses the column and shifts everything after it.
What carries over from Plain Text to Jira
Jira can express everything plain text holds about a table, so this conversion is about shape rather than loss.
Jira marks its header cells differently from its data cells, so the first row is written with that marker.
The identifier 007 comes out of the Jira as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.
The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a Jira file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the Jira.