Input data is written into textual input files in the ASCII encoding. Only the first 72 columns can be used on each line, further columns are ignored.
Acceptable characters (with the exception of comments) are upper and lower case letters of the English alphabet, numbers 0 to 9, space, and the characters + - , . ; ( ) = * : /. The following characters are equivalent to each other:
Input data is organized in batches and batches in groups. The order of the batches is not always fixed, as is the order of the groups in the batches.
A batch always starts with a pair of letters – the batch name. The batch name must be written in the first two columns of the first line of the batch. The entire batch can be written on one or more lines, with consecutive lines starting with two spaces. The batch ends with the name of the next batch, or with the end of the data of the last batch.
A group in the batch is delimited by separators. The separator can be a key letter or the / character. The last group of the batch is finished with the start of the next batch. The placement of separators on the line is not positionally bound in any way. Thus, several groups can be written on one line, or, conversely, one group can be written on several consecutive lines.
Numerical data can be entered in all usual ways. The plus sign of positive numbers can be omitted.
For real numbers, a comma can be used instead of a decimal point. Real numbers whose value happens to be an integer can be written without a trailing period. When using semilogarithmic notation, the mantissa must not be separated from the exponent with a space, i.e., there must not be a space before and after the letter E or e (this would cause the character to be understood as a key letter and not as part of semilogarithmic notation).
Only the digits 0 to 9 and the characters + - . , e E can appear in the numeric data. Any other character or the end of the line (i.e., the 72nd column) terminates the number.
Condensed notation can be used to enter numerical sequences whose values exhibit a simple regularity.
The rest of the line after a semicolon ; is not analyzed and can therefore be used to write comments for easier orientation in the input data. Comments can contain any characters.