Tag Attributes - Signage

Signage expected in the XBRL

By default, values in the XBRL must be positive. e.g. "Turnover" and "Cost of sales" are both expected to be positive but are usually shown with opposite signs on the accounts. The "Reverse signage convention" attribute is used in this case to turn a negative "Cost of sales" in the accounts into a positive "Cost of sales" in the XBRL.

Negative values are usually only expected when the tag can contain positive and negative numbers, such as "Gross profit / (loss)" or "Tax charge / (credit)". In these cases, it is usually not necessary to reverse the tag unless on the rare occasion the signage convention adopted in the accounts is opposite to what the taxonomy is expecting.

The XBRL signage expected can be determined by the tags label:

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In this example, despite the tags covering both income and expense items, the only negative value expected in the tags above would be if the company has suffered a gross loss.

Tags Which Usually Have to Have Their Signage Reversed

Facts in your accounts wbhich are inherently negative and usually have to have their XBRL tag signage reversed are as follows:

Expenses in the P&L
Creditors on the face of the Balance Sheet (if represented as negative)
Deductions (such as disposals & impairments)

Reversing a tag's signage

If the fact in the document has a signage convention which is opposite to the signage convention expected by the taxonomy, check the "Reverse signage convention" check-box.

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If checked, and the fact is positive, a negative value will be used in the XBRL instance document, and vice versa.

A practical example of this situation is “Cost of sales” in the UK GAAP taxonomy. As indicated by the tag label, a Cost of Sales value of e.g. 800,000 must be positive in the instance document. Often, this may be disclosed as (800,000) which is the opposite signage convention.

Furthermore, the balance attribute of the "Cost of sales" tag is a Debit. In the example above, because the signage in the report is negative, and the balance attribute is Debit, the interpreted signage will be a Credit which in this case is clearly incorrect. By clicking on the “Reverse signage convention” box, the interpreted signage will revert to a Debit:

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Report Authority can only indicate the interpreted balance if the taxonomy and the particular tag utilises the balance attribute. If they do not, “Not applicable” will be shown.

When tagging an entire row, e.g. the disposal row in a movement of tangible fixed assets note, simply use the shortcut key straight after tagging (Ctrl + Shift + v) [reVerse]. This will reverse each and every disposals tag in one action.