TXT files can be uploaded within your Assets as well as within a Project.
Key points regarding txt files, when used in a project, are:
TXT file type is not supported in review mode.
When uploaded to a project either as an Approval Asset or a Reference File, you will not be able to review or generate reports.
TXT files can be downloaded.
No thumbnail is generated.
Key points regarding txt files, when uploaded into the asset library, are:
TXT file type is not supported in preview mode.
TXT files can be added to an existing collection and added to a new collection.
TXT files can be downloaded.
TXT files can contain attributes.
TXT files are able to be shared via the Get Download Link feature.
TXT will appear as the asset thumbnail.