Speaking of CSV, SSV, TSV and so on similar file formats ... summarized under the term CSV format.
Regarding CSV file format there exist no normal practice at all, because there is no standard defined, but there are somewhat common behaviours around in the world.
You have to know, that Mp3tag is per se not CSV ready.
But Mp3tag can create an export script, which outputs a CSV formatted text file.
Mp3tag cannot auto-detect the format of an input file, which is a CSV file.
When using the converter "Textfile - Tag" the user has to define a specific set of field masks for the entire textline. This way a CSV format can be simulated.
For both cases, inputting data and outputting data, the user is responsible to provide the right format.
Do not forget that the xSV delimiter character may be regional depending, can be comma or semicolon, such like numbers with decimal point with thousand comma resp. decimal comma with thousand point.
The most important thing is, that the two involved applications can talk to each other via a common file format resp. data structure.
Mp3tag is free to give this decision to your own inspiration and systematics.
One method would be, to enclose all values into Double Apostrophes and choose a delimiter that is common between the sender and receiver application.
You have to take into account that Mp3tag as sender cannot automatically escape the Double Apostrophe, when a tag-field already contains a Double Apostrophe.
Same is valid for Mp3tag as receiver, when a CSV field contains an escaped Double Apostrohe, Mp3tag cannot automatically unescape this field data.
You have to write your own Escape/Unescape scripting sequence.
Another method would be - when the other application can understand - to use no Double Apostrophes at all and use any delimiter character, which is not used in any data field, for example choose one character from this set '*,|,÷,°,■,±,¦,¤'.
You can also use a three character delimiter sequence string between the data fields, for example ' ¤ ', if the other application can handle this.
DD.20110610.2028.CEST