Tables should be used to concisely display data (usually numbers) that can be meaningfully compared or tallied. Avoid as much as possible long tables with lots of lengthy paragraphs of text. Such information is usually best presented in other ways.
The document templates have styles for the different elements of the table. If you apply them correctly, then fonts will be set for you. Table headers should be Arial, 9 pt, bold, and have no background shading. Table text should be Arial 9 pt. Table footnotes should be Arial 8 pt.
Minimize the number of borders (rules) in your tables. There should be no vertical rules at all, and horizontal ones should be eliminated as much as possible. There should always be a rule above and below the table header and at the very bottom of the table. Other than that, only add horizontal rules if needed for readability.
The header row must be set so as to not break across pages and repeat at the top of every column or page.
Body rows should also not break across pages unless they contain many lines of text, but see point 1 above.
Headings should be set in sentence case.
Columns of text should align left. Columns of numbers should align right or on the decimal point.
Avoid rotated text. It is much harder to read. If your column headings are so long or the table so wide that you feel you need such techniques, consider instead breaking the table up or moving to a larger page size.
Minimize repetition as much as possible. If all numbers in a column are the same unit, for example, put the unit once in the column heading instead of repeating it in every cell.
If many of your cells in a column contain the same information, then reconsider if that column is helpful or if there is a less cluttered way of conveying the information (e.g., by stating a default value in the caption or column heading).
Order table footnotes based on how they appear if reading left to right, top to bottom.
Do not use numbers to indicate footnotes in tables. If there are no more than six notes, prefer symbols (the sequence is *, †, ‡, **, ††, ‡‡). Letters are preferred otherwise. Editing can help with this when the document comes in for formatting.
If the table data come from a particular source, put that information in an unnumbered table footnote, which should appear before any other footnotes.
Source: Petrinex, 2019
For notes that apply to the entire table, place that information in an unmarked table footnote preceded by the word Note. Don’t add a footnote to the caption. This unmarked note should come before any numbered notes. If there is both a Source and Note, place the Source line first.
Note: These data do not include emissions from oil sands mines.
Table footnotes appear at the bottom of the table itself, aligned with the left-hand edge. The “Table footnote” style in the template will format it properly.
The level of precision of your data should be consistent throughout the table. Perhaps refamiliarize yourself with significant figures.