An interactive, crosslinguistic database systematically documents the phenomenon of P-demotion across 55 genealogically diverse languages. P-demotion is observed in verb valency-changing alternations where the P argument (object) of a transitive construction loses its status as a core argument. This change in verbal valency may be encoded by a voice marker. The loss of the core status by the P argument manifests different across languages. For instance, it may involve changes in P-encoding properties, such as indexing and flagging, or the elimination of this argument from the valency slot, which may also alter its indexing on the verb. The phenomenon of P-demotion thus arises from the operation on verbal valency and results in a syntactically intransitive construction, where the demoted P-argument can be expressed as an oblique, incorporated, or fully eliminated. Given, that these constructions share two main features: (i) demotion of the P-argument and (ii) retention of the argument structure, where agents remain agents and patients remain patients, they naturally exhibit formal and/or functional overlap. The morphosyntactic strategy a language employs to demote the P argument depends on language-specific characteristics and functions associated with these strategies.

Based on the multivariate typology by Bickel (2010, 2011, 2015), which posits that every linguistic phenomenon can be decomposed into crosslinguistically comparable variables, the phenomenon of P demotion was systematically analyzed by breaking it down into formal and functional variables. Formal variables encompassed encoding properties of the core arguments A, P, and S in P-demotion alternations, such as flagging (e.g., case, adposition) and indexation (e.g., verb agreement, cross-referencing), along with the presence of voice marking and variation in P-oblique flagging. In contrast, functional variables were related to various types of P-demotion constructions alone and included properties of the P argument such as affectedness, referentiality, animacy, person, and number.

The database serves a dual purpose. First, it provides a comprehensive platform for exploring the grammatical properties (i.e., structural variables) of P-demotion constructions, thereby yielding valuable insights for comparative and crosslinguistic research. Second, it follows contemporary linguistic standards, including reproducibility, data sharing, and reusability.

Project members regularly cross-checked coding decisions to ensure consistency and accuracy. Additional strength of the database is the inclusion of a broad range of structural (formal and functional) variables, complete with values and corresponding source comments. These comments, cited directly from their sources, provide insights into the rationale behind specific coding decisions, where readers can easily consult the cited sources for further context on each variable.

Data for the interactive database was collected by three project members: Principal Investigator Katarzyna Janic, Co-Investigator Krzysztof Stroński, and Ph.D. student Mohammad Tavakoli. The development of the database application was a collaborative effort led by Maciej Danielak and Paweł Przybysz, who worked closely with Katarzyna Janic to (i) design and build the database architecture, (ii) process and integrate data into the system, (iii) select and implement appropriate technologies, and (iv) conduct testing to identify and resolve potential errors prior to public release. The Principal Investigator also established a data verification procedure, under which project member Wojciech Zeyland reviewed and refined data entries to ensure accuracy and address any inconsistencies.