The allowable range of ratios varies between barcode formats and also, for hardware barcodes, the output device. The template must not specify a value outside the allowable range. The parser ignores this property for barcode formats which do not allow a variable ratio of wide to narrow bar widths.
Reference_Syntax.wideNarrowRatio = “3:1 | wide[:narrow]“
3:1 (default)
wide[:narrow]
where wide is a positive number representing the numerator of the ratio, and narrow is an optional positive number representing the denominator of the ratio.
Form Model

wideNarrowRatio