The data file must be tab("\t"), space(" ") or semi-colon(";")-delimited, with column names (if exist) in the first row. Alleles should be separated with a slash "/", and column names cannot begin with a number.
Missings can be codified either with string "NA", NULL (empty) values, or a new specified string.

An example of a data file could be the following:
id	snp1	snp2	snp3	snp4	status	sex	age	cat.bmi
1	C/C	G/G	A/G	C/C	Co	Female	74	[25.9,29.0)
2	C/C	G/G	A/A	C/G	Co	Male	50	[16.0,23.6)
3	C/C	G/G	A/G	C/G	Co	Female	64	[16.0,23.6)
4	C/C	G/G	A/A	C/C	Ca	Male	67	[16.0,23.6)
5	C/C	G/G	G/G	C/C	Co	Female	80	[29.0,52.2]
6	C/C	G/G	A/G	C/C	Co	Male	79	[29.0,52.2]
7	C/C	G/G	A/G	C/G	Ca	Male	83	[16.0,23.6)
8	C/C	G/G	G/G	C/C	Co	Male	53	[23.6,25.9)
9	C/C	NA	G/G	C/G	Ca	Male	70	[25.9,29.0)
10	C/T	G/G	G/G	C/G	Ca	Male	62	[25.9,29.0)