**Table of Contents**

### What is Sign Logic?

Sign Logic is a set of options to explicitly tell the Tagger how to report a tagged value (also known as the XBRL Value, Fact Value or Parsed Value) as positive or negative. You may need to change this depending on the context of your reporting.

When you get an Invalid Calculation message, one of the things you can check is the Sign Logic applied to the tag(s) included in the calculation.

### How do I pick the correct Sign Logic for a tag?

The following guidelines will give you a good understanding of how to select the correct Sign Logic.

The Sign Logic 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.

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 will be automatically applied and it cannot be changed, unless the tag and/or the summation tag has the balance type *Unknown*.

There are five options in the Sign Logic drop-down:

- None: no sign logic will be applied.
- As Reported: the value will always be added to the iXBRL document with the same sign as written 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 always be reversed. Negative values will be reported as positive values and positive values as negative values.

### Sign Logic options

The table below shows all the possible outcomes of positive and negative values, positive and negative weights and Sign Logics. 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. You can use this to work out which Sign Logic option to use.