Restocking - Phosphor Bronze String, Round Thread, 056 Dunlop acoustic sets...
Restock - 80/20 Bronze .056 Acoustic String, Spun Dunlop acoustic sets...
Restocking by 6 pieces - Round yarn 056
Restocking by 6 pieces - Round yarn 056
Restocking by 6 pieces - Round yarn 056
Restocking by 6 pieces - Phosphor Bronze Spun 056
Restocking by 6 pieces - Bronze Spun 056
Replacement per unit - Round yarn 56
Restocking by 12 pieces - Lifespan SP 80/20 unit rope .056
Restocking by 12 pieces - Lifespan SP 92/8 unit rope .056
Restocking by 12 pieces - SP 80/20 unit rope .056
Restocking by 12 pieces - SP 92/8 unit rope .056
The "0.56" measurement you mention is probably the guitar string gauge, also called string thickness. Guitar strings come in different gauges, which determine the thickness of the string and thus its tension and tone.
In general, folk guitar strings have gauges ranging from .010 inches to .013 inches. A string with a gauge of .56 would be extremely thick for a folk guitar and would not be considered standard or even common. In fact, most folk guitar strings have gauges ranging from 0.012 to 0.053 inches.
It is possible that the .56 measurement you saw is in millimeters rather than inches, in which case it would be an extremely thin guitar string. In any case, it is important to check the gauge measurement on the package or with the manufacturer before purchasing strings for your guitar.