File formats are staggeringly diverse. At Lokad, our ambition is to support all the (reasonable) tabular file formats. We were already supporting CSV (comma-separated values) files with all their variants - which can involve varying separators or varying line returns.
However, tabular files can become very large, and in order to make the file transfer to Lokad faster, these files can be compressed. Lossless compression of flat text files works very well, frequently yielding a compression ratio below 10%, i.e. the resulting compressed file is less than 10% of the original file.
Then again, compression formats are staggeringly diverse as well. So far, we were only supporting the venerable and ubiquitous GZip - the compression format used to compress web pages for example.
The two formats WinZip - famous for its .zip file extension - and 7z - one of the most efficient compression algorithms available on the market - are now supported by Lokad. In both cases, the file formats are archive formats, hence, a single .zip file can contain many files within the archive. For now, Lokad only supports single-file archives.
This choice makes sense in practice because if the flat file is so large that it requires compression in the first place, producing an even bigger archive gathering multiple large files tends to be impractical. Instead, we suggest to use incremental file uploads.