The Flexible Image Transport System ([[FITS|FITS)]]) standard is a widely used data format in astronomy that incorporates metadata and ASCII or binary data in the same file.<ref>{{cite journal |last1=Wells |first1=D. C. |last2=Greisen |first2=E. W. |last3=Harten |first3=R. H. |title=FITS: A Flexible Image Transport System |journal=Astronomy and Astrophysics Supplement Series |volume=44 |pages=363–370 |date=June 1981 |bibcode=1981A&AS...44..363W}}</ref> However, the FITS standard has several limitations that make it difficult to use for complicated and hierarchical data. For example, the FITS 'cards' have keywords limited to only 8 characters, which can make it difficult to properly describe the value associated with it and the value for each keyword and its comment cannot be longer than 68 characters.<ref name=Greenfield2015 /> By using [[YAML]], more sophisticated and nested data structures may be used in ASDF than FITS.
