The csv module implements classes to read and write tabular data in CSV format. It allows programmers to say, “write this data in the formatpreferred by Excel,” or “read data from this file which was generatedby Excel,” without knowing the precise details of the CSV format usedby Excel.

What if I want to know??

All kidding aside, I want to know specifically which attributes and settings would create the dialect csv.excel_tab

Dialect.delimiter A one-character string used to separate fields.

Dialect.doublequote Controls how instances of quotechar appearing inside a field should themselves be quoted.

Dialect.escapechar A one-character string used by the writer to escape the delimiter if quoting is set to QUOTE_NONE and the quotechar if doublequote is False.

Dialect.lineterminator The string used to terminate lines produced by the writer. It defaults to '\r\n'.

Dialect.quotechar A one-character string used to quote fields containing special characters, such as the delimiter or quotechar, or which contain new-line characters.

Dialect.quoting Controls when quotes should be generated by the writer and recognised by the reader. It can take on any of the QUOTE_* constants (see section Module Contents) and defaults to QUOTE_MINIMAL.

Dialect.skipinitialspace When True, whitespace immediately following the delimiter is ignored. The default is False.

Dialect.strict When True, raise exception Error on bad CSV input. The default is False.

Going straight to the source of Lib/csv.py, excel-tab has all the properties of excel, plus a tab-delimiter.

class excel(Dialect):"""Describe the usual properties of Excel-generated CSV files."""delimiter = ','quotechar = '"'doublequote = Trueskipinitialspace = Falselineterminator = '\r\n'quoting = QUOTE_MINIMAL
register_dialect("excel", excel)class excel_tab(excel):"""Describe the usual properties of Excel-generated TAB-delimited files."""delimiter = '\t'
register_dialect("excel-tab", excel_tab)