Table 1.

List and count of modifiers organized in 4 levels: R (REPLACE), S (SPLIT), D0 and D1.

Description	n
Level R: Modifiers preventing terms from being mapped to disorders Modifiers for substitution patterns (one-to-one) 1st => first, 2nd => second, 3rd => third, 4th => fourth, 5th => fifth	5 (present in 1,193 HPO terms)
Level S: Modifiers preventing terms from being mapped to disorders Modifiers for substitution patterns (one-to-two) Terms containing a “/” are split into two terms, for example: Aplasia/Hypoplasia of kidney => Aplasia of kidney; Hypoplasia of kidney	69 (present in 543 HPO terms)
Level D0: Modifiers preventing terms from being mapped to disorders asymmetric, asymmetrical, bilateral, complete, congenital, cutaneous, generalized, lethal, marked, mildly, multiple, nearly, osseous, partial, patchy, severely, symmetric, symmetrical, unilateral, Alcohol-induced, Aminoglyco-side-induced, Anesthetic-induced, Aspirin-induced, Cold-induced, Drug-induced, Effort-induced, Exercise-induced, Fava bean-induced, Heparin-induced, Radiation-induced, Stress-induced, infection-induced, Viral infection-induced, Warfarin-induced, “, recurrent”, “, acute”, “, chronic”	37 (present in 1,129 HPO terms)
Level D1: Modifiers preventing terms from being mapped to anatomical structures/physiological processes/chemical substances abnormal, abnormality, absence, absent, activity, agenesis, aplasia, aplastic, atresia[s], atrophy, bracket, broad, bullet shaped, bullet-shaped, chevron shaped, chevron-shaped, cone shaped, cone-shaped, contractures, curved, decreased, deficiency, degeneration, delayed, duplication, dystrophy, eeg, elevated, enlarged, fragmentation, hypoplasia, hypoplasic, hypoplastic, impaired, increased, irregular, ivory, loss, lytic defect[s], malrotation, number[s], osteolytic defect[s], prominent, pseudoepiphysis, reduced, rhomboid shaped, rhomboid-shaped, rudimentary, sclerosis, shortened, shortening, small, sparse, stippling, symphalangism, synostosis, thin, triangular, triangular shaped, triangular-shaped, wedge shaped, wedge-shaped, widened, widening	65 (present in 8,864 HPO terms)