Dyshidrotic eczema is not linked to asthma. only atopic eczema is linked to asthma( hence the term "atopic march") is this correct?

Yes that's correct: atopic march explains natural history of allergy progression in atopic individuals, while dyshidrotic eczema is different usually has no known cause, and treatment is different, but an individual can have the condition and have asthma too as two separate conditions not necessarily linked

Asthma separate ...: Dyshidrotic Eczema, sometimes called Pomphoylx is an itchy skin condition of the hands and feet, characterised by vesicles, fluid filled bubbles. It is distinct from Atopic Dermatitis / Eczema which is associated with Asthma and Hayfever. A diagnosis of Dyshidrotic Eczema should not increase your risk of developing Asthma above and beyond that of the general population (about 3.8/1000 adults/yr).