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What are Common XBRL Syntax Errors?

Here are common XBRL syntax errors we find when we examine XBRL filed with the SEC:

Definition Missing

This is the most common error where no definition is included with an extension. The XBRL vendor does not put in a definition on a company extension tag.

  • Possible Problem: Analysts examining the XBRL will put their own interpretation on the item.
  • Fix: Simply add a short description on the tags. One sentence explaining why you are extending this tag will help the analyst understand your business.

Deprecated Tag

This is the second most common error. For legacy reasons, when rolling taxonomy, taggers will often use the previous set of tags.

  • Possible Problem: Analyst programs may not find your line item. Your filing also looks out of date.
  • Fix: The deprecated tag will often (not always) have suggestions for a replacement tag. Consult the SEC's taxonomy or other software to verify your tags and pick the suggested tag.

Incorrect Data Type

We have seen cases where the actual data's unit does not match the data type of a US GAAP or company extension tag. We have seen monetary units in percentage data types.

  • Possible Problem: You will have trouble including these data items in calculation link bases. Further analyst program may throw exceptions if encounter such fields.
  • Fix: Inspect data unit against the tag's data type. Your vendor should be able to correct your data to match a tag's data type.

Unnecessary or Duplicate Extension

We have seen extensions that are duplicates of US-GAAP. The tag is of the form: fil_AssetsCurrent where a us-gaap_AssetsCurrent already exists.

  • Possible Problem: The SEC frowns on use of extension if it duplicates us-gaap tags. You may get a letter from the SEC for using such tags.
  • Fix: If you tag describes an item unique to your company, change the tag and apply the appropriate description. If not, select the us-gaap tag. Search the taxonomy for the same tag and replace your extension with the us-gaap tag.

Incorrect Period Type

A company extension tag will have a period type that doesn't match the data-type. The most common occurrence of this is with company extension of textblock data-type. The SEC recommends using duration for textblock fields.

  • Possible Problem: Using the wrong period type results in incorrect date ranges being applied to a field.
  • Fix: Modify your extension to have the SEC recommended period type. Change the date range to reflect this period type.

Schema Error

A table may be misclassified. For instance a notes table may be marked as a Statement instead of a Disclosure.

  • Possible Problem: Analyst programs reading the XBRL may throw exception.
  • Fix: Ask your vendor to classify the table correctly.

Concepts not in requisite Linkbases

Concept is not in all linkbases. For instance a concept is in the presentation and definition linkbases but not in the label linkbase.

  • Possible Problem: The concept may not be displayed properly by XBRL rending programs.
  • Fix: Ask your vendor to add the concept in all the required linkbases.

Missing Domain

A dimension does not have a domain.

  • Possible Problem: Dimensions are not displayed or located accurately.
  • Fix: Ask you vendor to add the appropriate domain.

Definition Linkbase Error

In a dimension, a member tag is placed under an Axis instead of a Domain.

  • Possible Problem: Dimensions are not displayed or located accurately.
  • Fix: Ask you vendor attach the member tag to a domain.

Extension tag is not marked as abstract

The extension tag is not explicitly specified as an abstract tag. We often see this in dimension tags where the abstract property is missing from the tag's definition.


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