Can a 18x20 String Pattern Be Open?

Before the popularity of spin patterns (eg 16x15), there were only two dominant string patterns - 16x19 or 18x20. The former was known as an "open pattern" and the latter a "closed/dense pattern".

But can those definitions of open or closed be universally applied to all 16x19s and 18x20s?

Even with the same racket headsize, I found it was not so straightforward. 

Take a look at the 18x20 ProKennex Black Ace 98 versus the 16x19 Dunlop M-Fil300 below. Both are 98 square inches.

If you examine the string gaps carefully, it would be difficult to ascertain which racket's string gaps are larger, isn't it? The difference is so minute!

The total width of the 18 main strings in the BA98 is about 19.1 cm. For the Mfil300, the 16 mains are about 18.1 cm apart. So on average, each racket's main string are about 1.06 cm and 1.13 cm apart, respectively. With a tiny difference of only 0.07 cm, or 0.7 mm!!!

What about the cross strings' gap then?

All the crosses in the BA98 span over 25.5 cm versus 24.0 cm for the Mfil300. This translates to an average cross string gap of about 1.275 cm and 1.263cm respectively.

To me, both rackets have equally open strings!

It is very important to dispel the generalizations between open and closed string patterns because this has huge implications on tension and string selection, which in turn determines spin, power, string durability, comfort and control.