The staff in the Commission’s Division of Economic and Risk Analysis (DERA) analyzed eXtensible Business Reporting Language (XBRL) exhibits  submitted by issuers complying with the 2009 Interactive Data rules requiring financial statement information to be filed in an XBRL format. Our analysis covered XBRL exhibits submitted with forms 20-F, 20-F/A, 40-F and 40-F/A from January 2017 to December 2018 by filers reporting in International Financial Reporting Standards as issued by the International Accounting Standards Board.  The purpose of the analysis was to analyze trends in filers’ use of custom tags in their XBRL exhibits for the aforementioned forms during 2017 and 2018 in two folds: 1) Financial statements (F/S) only and 2) F/S and notes.
The Commission’s rules allow filers to create custom tags when the standard taxonomy does not provide a tag for the necessary financial element. While this customization accommodates unique circumstances in a particular filer’s disclosure, the Commission has acknowledged that the use of unnecessary customized tags could potentially reduce the comparability of data across filers.  Thus, the Commission’s rules specify limited circumstances under which a filer may create custom tags. 
DERA staff intends to continue reviewing filers’ use of XBRL in their submissions to the Commission. Depending on the results of those efforts, DERA staff may share additional trends, issue guidance, or pursue other actions.
For the staff’s previous trend analyses on custom tags, see the Staff Observations, Guidance, and Trends page at https://www.sec.gov/structureddata/osdstaffobsandguide. For the staff’s 2014 observations on custom tag rates, see http://www.sec.gov/dera/reportspubs/assessment-custom-tag-rates-xbrl.html.
DERA staff welcomes your questions and comments. Please feel free to email us at StructuredData@sec.gov or call us at (202) 551-5494.
 7 of 860 forms included in the analysis represent Inline XBRL filings as of July 9, 2019.
 Release No. 33-9002 (Jan. 30, 2009), 74 FR 6776 (Feb. 10, 2009) (“2009 Rule”).
 Our analysis includes custom tags of line items and excludes tags that are abstract, text-related, member, domain, and document and entity. For definitions of abstract, member, and domain, see XBRL glossary at https://www.sec.gov/page/osd_xbrlglossary. Document and entity tags are largely related to identification and classification of filers and include, among other things, form type, company name, filer size, and public float.
 See 2009 Rule at 104-105.
 See 17 CFR 232.405(c)(iii) (B) (“An electronic filer must create and use a new special element if and only if an appropriate tag does not exist in the standard list of tags for reasons other than or in addition to an inappropriate standard label.”).