What coat pattern is characterized by white markings that are speckled and flecked?

The coat pattern characterized by white markings that are speckled and flecked is known as sabino. This pattern typically appears as irregular white patches or markings on a horse’s coat and can vary in the size and shape, with some areas appearing more densely marked than others. Sabino horses often have a distinctive look, with spots of white that are not simply "blotched" like other patterns but give a speckled appearance, which aligns with the description of the question.

In contrast, the other coat patterns do not fit this description. Spotted typically refers to patterns with uniform spots of color, checkered is an arrangement that often implies a squared pattern, and mottled commonly describes a more blended or splotchy appearance rather than the distinct flecks characteristic of sabino. Hence, the sabino pattern stands out as the correct identification for horses with such speckled and flecked markings.