Propositus, prepositus, praepositus

In reading ahead for my third year subject of Wills and Succession I feel that reserva troncal will be an exciting but contentious topic.

Here's how Paras in Civil Code of the Philippines, Annotated, Vol. III, 2013 Edition diagrammed the matter on page 314:

And here's the diagram by Ruben F. Balane in his book Jottings and Jurisprudence in Civil Law (Succession) 2010 Edition on page 363:

Similar diagrams but on the next page Balane uses Prepositus while Paras uses Propositus.

I checked up on Jurado and he is on the side of Paras. Vitug uses Praepositus  from which, I think, Balane got his variant of the Latin word.

A google search shows that Paras and Jurado are correct. Propositus according to Dictionary.com means the person  from whom a line of descent is derived on a genealogical table.  

Praepositus means commander. chief, provost, etc. (see here and Meriam-Webster Dictionary).