>>24853350
But a more recent "Introduction to the Grammar of Sumerian" by Gabor Zolyomi (2018) definitely states this prefix denotes spatial closeness or direction towards the speaker. The big downside of this book is that it doesn't use cuneiform at all. So if I continued the study of Sumerian, I'd use Hayes' as the primary textbook and would consult Zolyomi's regarding specific grammar points after each lesson.