| Which script the source uses | Modern documents are Latin, Soviet-era ones Cyrillic or Russian, and South Azerbaijani ones Perso-Arabic. Read only one era and you mistranscribe stamps, authority names and marginal notes from the other. | A specialist first identifies the script, then reads Latin, Cyrillic and Perso-Arabic sources and reconciles names and authority names across them. |
| The schwa letter Ə ə | Ə (the sound /æ/) is often flattened to "a" or "e": Əliyev becomes "Aliyev" or "Eliyev". In Cyrillic it was Ә, and the passport may spell it a third way — three versions of one person. | We keep the document's ə form and record the passport spelling, so both versions are tied to the same person. |
| Dotless ı vs. dotted i | Azerbaijani — like Turkish — distinguishes ı (no dot) from i (dotted), and capital İ from I. A swapped dot turns one name into another and breaks the registry match. | The i-dotting is set character-exact from the source document, not adjusted to a German or Turkish keyboard habit. |
| Treating Azerbaijani as "Turkish" | The two are close but distinct: own vocabulary, the ə, Russian loanwords, different official and legal terms. A Turkish stand-in misses technical terms and authority names. | Azerbaijani native speakers with a field do the work — never a Turkish-variant treatment. |
| Patronyms -oğlu / -qızı vs. russified -ov / -ova | Soviet papers carry russified endings (-ov, -ova, -yev); traditional and current names use -oğlu ("son of") and -qızı ("daughter of"). Within one family's documents both forms appear. | Each document's name form is transferred exactly, and diverging variants are matched to the same person. |
| Vowel harmony & agglutination | Case, possession and number ride as suffixes governed by vowel harmony. Split apart literally, references are lost — whose document, how many, in what relation. | Specialists resolve the agglutinated forms into unambiguous German relations, grammatically correct. |
| Issuing bodies & authority names | Many current civil-status certificates come from the state service centres ASAN xidmət; Soviet ones from the ZAGS office. Not knowing the bodies, you render stamps and notes wrongly. | We know both the current and the Soviet issuing bodies and transfer authority names, stamps and marginal notes correctly. |