Delimiter

The character that marks where one field ends and the next begins — and the specific problem that happens when your data contains that character too.

What it is

A delimiter is a character used to mark the boundary between separate pieces of data within a larger structure — most commonly, between columns in a row of tabular data. In name,role,city, the comma is the delimiter; it's what tells a parser where one field ends and the next begins.

Common delimiters

• Comma — the default for CSV (Comma-Separated Values), the most common plain-text tabular format.
• Tab — used by TSV (Tab-Separated Values); tabs rarely appear inside the data itself, which makes tab-delimited files less prone to the escaping problem below.
• Pipe (|) and semicolon — used in regions or systems where the comma is already reserved for something else, such as locales where commas are decimal separators in numbers.

The problem delimiters create

A delimiter only works if it doesn't appear inside the data itself. A CSV file listing addresses runs into trouble the moment an address field contains a comma: 123 Main St, Apt 4,Springfield looks like four fields instead of two. The standard fix is quoting — wrapping any field that contains the delimiter in double quotes, so a parser knows to treat the comma inside the quotes as literal data rather than a separator: "123 Main St, Apt 4",Springfield. A parser that doesn't correctly implement quote-handling will misread files like this, silently shifting every column after the affected one.

Detecting the right delimiter automatically

Given a block of raw pasted data with no explicit format specified, a converter has to guess which character is functioning as the delimiter — typically by checking which candidate character (comma, tab, semicolon, pipe) produces a consistent number of fields across every row. Rows that don't agree on a field count under a given delimiter guess are a strong signal that delimiter is wrong.

Where this shows up

The Markdown Table Generator auto-detects the delimiter in pasted CSV or TSV data before building the aligned output table. The bulk file converter's CSV handling relies on correct delimiter parsing to know where one column ends and the next begins before extracting and converting the first column.

Source

RFC 4180 — Common Format and MIME Type for Comma-Separated Values (CSV) Files, IETF. Worth noting: RFC 4180 itself states there is no single universally-followed "master" specification for CSV — it documents the closest thing to a common convention, not a strictly enforced standard.

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