Every market on the Data page is checked as you work on it. The checks are simple arithmetic and completeness tests - the things that are easy to get wrong in a spreadsheet and awkward to explain later - and a market can't be confirmed until they pass.

Where to find them

Data validation sits above the market's figures. When everything passes it's quiet; when something doesn't, it turns into a red issue count.

Click it to see where you stand. Nothing blocks confirming this market means you're clear.

The checks are:

• Companies add up to no more than the Total - named companies can't exceed the market size.

• No negative values.

• No duplicate companies - the same company twice would double-count its share.

• Every company row has a name and every company has a value.

• Total is entered and at least one company is entered.

Markets with children get parent-market checks too; where they don't apply, the panel says so.

When something fails

The panel names the problem in plain terms - which company, which figure, what's wrong with it - and usually offers the fix next to it, so a stray minus sign is one click rather than a hunt through the table. The checks that did pass are listed underneath, so you can see the rest of the market is sound.

Click the red message itself and Sloc takes you to the figure it's complaining about and selects it, ready to edit. On a market with a dozen companies that saves reading the table line by line - and it's the route to take when the suggested fix isn't the one you want.

Where more than one check fails, each gets its own message and its own fix, and the fix is specific to what's wrong. A market whose companies add up to more than the total is offered the total those figures imply - accept it, or go and find the company that's overstated.

Clicking that message highlights the Total row rather than a company, because the total is the figure being tested. The message always points at what the check is actually about.

A market with an issue also drops out of Confirmed and goes back to In progress, which is deliberate: anything you've already signed off stops being signed off the moment its figures stop adding up.

Finding them all

The Market queue on the left counts markets by status, and the error chip filters the list to the ones that need attention - with the number of errors against each market. On a version with hundreds of markets, that's the worklist.

Pro tips

• Work the error chip to empty before you start confirming. Fixing as you go beats a sweep at the end.

• Companies exceeding the total usually means a mismatch of units or years, not a typo. Check what the figures actually measure before you adjust one.

• A one-click fix still changes the data, and Sloc records that it was you - see how to see where your data came from.

• Checks test arithmetic, not judgement. A market can pass every one and still have the wrong companies in it.