Since most SEISAN programs are written in Fortran, the format descriptions follow the Fortran convention. The following are the main format descriptors:

**I**n: Integer format: E.g. I5 means an integer with 5 digits normally right justified. A completely blank field will be read as zero. Examples:

123456.. (Position) 1100 read as 1100 11 read as 11 read as 0

**F**n.k: Real number format: E.g. f7.3 is a real number occupying 7 places like 111.111 and the decimal point is 3 places from the right. Any real number can occupy the 7 places like

1234567 (Position) 1.1 1.1 1.1

All of these will be read as 1.1. If there is no decimal place given, it is automatically put k places from the right. Like the number 1234 read with f4.2 will be read as 12.34.
nX . Spaces. Like 5x means 5 spaces.

An: Character format: Like A5 means reading 5 characters

Combining format specifications, example

1234567890123456789 position 2f5.1,1x,a4,2x,i2 11.1 12.1 text 12

Do not use tabulator instead of blanks