Numer archiwalny (Archival reference number) the reference number of operative case-files and personal files kept in the archives of the Security Service (SB) "C" division, consisting of the consecutive number of the file inventory, i.e. the archive log (under which archived files were entered in chronological order), followed by the log symbol after the slash, corresponding to the category of operative or personal files. The archival reference number was unique. From 1968, agent files had references: No./I (with regard to TW, KO, KS, holders of LK and MK, trusted persons, OZI, etc.) or No./I-k in the case of KTW; operative case-files: SOS, SOR, KE, TEOK: No./II; investigations and inquiries (investigation control files): No./III; object case-files: No./IV; personal files were given the following reference symbols – personal dossiers of Security Service (SB) officers: No./V; personal dossiers of Citizens' Militia (MO) officers: No./VI; personal dossiers of civilian employees of the Ministry of the Internal Affairs: No./VII; personal dossiers of professional soldiers of the Ministry of the Internal Affairs: No./VIII; personal dossiers of employees of the State Fire Service Headquarters: No./IX. Archival reference numbers could also be recorded as I-1234, IV-1234, 1234-II etc. Files produced by the Citizens' Militia (MO) and Border Protection Troops (WOP) and Internal Military Service (WSW) of the military units of the Ministry of the Internal Affairs additionally included the letters: "m" (for MO) and "w" (for WOP and WSW of the Military Units of the Ministry of the Internal Affairs), respectively. Dossiers of the persons allowed to take an official position abroad were labelled with the relevant archival log consecutive number followed by the letter "A" after the slash; operative case-control dossiers were labelled with the archival log consecutive number followed by the letter "K" after the slash. When a file was microfiched or microfilmed, the microfilm was given a new archival reference number, consisting of the consecutive number of the microfilm inventory/log – usually, the former archival number of the filmed file followed by the Arabic numeral after the slash, corresponding to the Roman symbol of the relevant file inventory (archival log), i.e. a file with the reference 1234/I corresponded to microfiche with the reference 1234/1 or 1-1234 etc. A separate record of microforms was kept by the Ministry of the Internal Affairs so that the file reference numbers do not in every case correspond (apart from the equivalent archival log symbol) to those of microfiche. In the archives of Department I of the Ministry of the Internal Affairs, operative case-files, when archived, were assigned archival reference numbers of only one series – in the order in which the files were received in the archive, without dividing them into categories or giving separate archival log symbols. From the beginning of the 1970s, in the archives of Department I of the Ministry of the Internal Affairs, microfilms of files were assigned a “J” number, which later de facto replaced the original archival reference number of the file.