"[M]editation refers to a family of self-regulation practices that focus on training attention and awareness in order to bring mental processes under greater voluntary control and thereby foster general mental well-being and development and/or specific capacities such as calm, clarity, and concentration" Walsh & Shapiro (2006)
"[M]editation is used to describe practices that self-regulate the body and mind, thereby affecting mental events by engaging a specific attentional set.... regulation of attention is the central commonality across the many divergent methods" Cahn & Polich (2006)
The practice of 'coding in the zone' might as well achieve the same effect as traditional meditational practices and be called meditation on that ground. In fact, you are training the control of your attention with that practice.