The problem of placement concerns the spatial position of interaction objects (IO) such as edit box, radio button, list box, … with respect to visual elements in a screen layout. Effective placement can be achieved through a particular placement strategy involving a certain amount of visual techniques such as proximity, alignment, separate reference, centering, and conformity. For instance, Galitz suggests a placement strategy where IOs should be placed according to their nature: In this paper, the placement is defined as the description of a composite IO (e.g. a form container widget) for displaying IOs to be placed relatively to one another. Composite IOs generally allow IOs to resize themselves as the composite resizes.
Vanderdonckt, J., Ouedraogo, M., & Ygueitengar, B. (1994). A Comparison of Placement Strategies for Effective Visual Design. People and Computers IX, p. 125-144. https://doi.org/10.1017/cbo9780511600821.011