What defines complete digestion?
Complete digestion represents reaction endpoint where every copy of the DNA molecule in the sample has been hydrolyzed at all cognate recognition sequences. No uncut or partially cut intermediates remain. On gel this yields crisp bands whose number follows n for circular and n+1 for linear DNA, with fragment sizes summing to parent length. Ladder pattern indicates partial or multiple sites, absence of cut shows failed reaction, single band may reflect linearization or co-migration. The defining criterion is saturation of all target sites by active enzyme under optimal buffer conditions.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.