Formula fields in tables

• A table column can be a Formula, worked out from each row's other fields, Airtable style: {Price} * {Quantity}, IF({Due} < TODAY(), "Overdue", ""), DATETIME_DIFF({Due}, TODAY()). 44 functions for logic, numbers, text and dates, named and written as in Airtable (DATETIME_DIFF counts days unless you give it another unit).
• The editor lists the table's fields and the functions, and as you type says what the formula gives on the first rows, or what's wrong and where.
• Values are worked out on the server each time a table is read and never stored, so the grid, board cards, a table embedded in a doc, guest links, the chart and questions asked of a table all read the same values. TODAY() is today where the reader is.
• Renaming a field doesn't break the formulas that use it; deleting one shows it as {Deleted field}, with the reason in every row. A formula can read another formula; one that reads itself, even through another, isn't allowed.
• Limits that keep a heavy table from slowing the server: text a formula puts together (&, CONCATENATE, REPT, SUBSTITUTE) can be up to 10,000 characters, and LEFT, TRIM, UPPER and the rest work on cells of any length; a table can have up to 100 formulas; a formula that takes too much working out says so in its cells.
• API: field type formula with config {"formula": "…"} (sent and received with field names, stored by field id); POST /tables/{id}/formula/preview; the table endpoints take ?tz= for TODAY(). Migration 196.

Sort and filter tables

• Sort and Filter above a table's grid, board and calendar. Sort by up to three fields; filter with the conditions each field takes (contains, =, >, before, ticked, has, empty…), matching all filters or any. "Showing 3 of 12 rows" says when some are hidden. Each person's sorts and filters are kept in their browser for that table.