What is SignLogic?
SignLogic is a set of options to explicitly tell the Tagger whether to report a XBRL numberThe XBRL number is the reported value, and its sign may be different from the sign used in the PDF version of your report. Read Section 5 of the IFRS Preparer's Guide: Reporting negative values for IFRS taxonomy elements - for more information on reporting negative numbers. as positive or negative. You may need to change this depending on the context of your reporting or if a value is being used in a calculation.
When you get an Invalid Calculation error, or your calculation doesn’t add up correctly, you will need to check the SignLogic applied to the cells involved in the calculation. Please be aware Invalid Calculation errors are only Warnings. This type of error does not have an impact on your final report and, subject to taking advice from your auditors, can be disregarded or the calculations removed.
How do I pick the correct SignLogic for a cell?
The following four rules will give you a good understanding of how to approach picking the correct SignLogic for each cell in your report. Please be aware that, although each cell has a SignLogic value, the default value of Always Positive is usually correct (see Rule #3 below). Following these rules are some examples and a table that explains all the possible outputs of the different SignLogic options on credit and debit tags with positive and negative numbers.
Rule #1 - It doesn’t matter how the number is written in your report
The SignLogic option you need to pick may very well be different from how the number is written in the report. It will always depend on how the number is intended to be reported and the specific circumstance of the reporting. For example, in the sentence “We reported a loss of £5,123” the number itself is written as a positive but is intended to be understood as a negative number.
Rule #2 - You cannot change the weight of a tag
When you add tagged cells to a calculation you will see that each tag has a weight of either +1 or -1. This weight shows whether the balance of the tag is credit or debit and applies the corresponding +/- sign to the reported value. The correct weight/sign will be automatically applied and it cannot be changed. To change how the Tagger is interpreting a number you must change the SignLogic. You can do this in the Table Cell Properties tab.
Rule #3 - Different SignLogic options mean different things
There are five options for SignLogic:
- None: no special sign logic will be applied.
- As Reported: the value will always be added to the iXBRL document with the same sign as the sign in the report.
- Always Positive: the value will always be reported with a positive sign.
- Always Negative: the value will always be reported with a negative sign.
- Reverse: the sign will be reversed. Negative values will be reported as positive values and positive values as negative values.
As explained in the video above, you should only need to use AsReported and Reverse.
The table below shows all the possible outcomes of positive and negative values, positive and negative weights and SignLogics. As such, some of these combinations are not ones that you would want to use in your report - they are included for illustrative purposes only. Use this to work out which SignLogic option you need to use:
You can run out your own version of this table for your report by clicking Options/Calculation Report from the Tagger top menu bar. This will create an Excel file with columns for Shown Value, Parsed Value, SignLogic and Calculated Value where it’s easy to see if a number has the wrong sign. If you have multiple tables in your file each table will be shown in its own tab.