The straight line with dotted line underneath means Dc, also to the left of the red circle gophert drew there is a diode symbol, depicting a rectifryer, so your weld set certainly is Dc.
Other things you can do, an Ac weld set would show very little voltage with a multiometer set to Dc, but full 50v or more ac voltage set to Ac.
Also when using a Ac mig you can hear a fairly loud buzzing noise from the arc, Dc is more of a crackle.
There are raw 50/60hz 'mig' sets out there, I wouldnt like to try and weld with one.
Gasless takes a lot of getting used to.