What are uncommon tabular formats?

[MJSher]

One of the requirements for access level 3 is to load a file from an uncommon tabular format. Are the common tabular formats just the ones listed in level 2 (which are .csv, .tsv, .dat, .database, and .json)? If so, does that mean the excel format (.xls) is an uncommon tabular format?

[brownsarahm]

for the purpose of this case, yes excel is uncommon (it is common in some senses, but it is unruly so it is commonly avoided)

[MJSher]

Alright, thank you! I was just wondering because I tend to see .xlsx files often