[MODESTINUS libro secundo pandectarum. ] §28.6.1.preredes aut instituti dicuntur aut substituti: instituti primo gradu, substituti secundo uel tertio.
[MODESTINUS in the second book of the Pandects.] Heirs are called either instituted or substituted: the instituted in the first degree, the substituted in the second or third.
H §28.6.1.1eredis substitutio duplex est aut simplex, ueluti: 'Lucius Titius heres esto: si mihi Lucius Titius heres non erit, tunc Seius heres mihi esto': 'si heres non erit, siue erit et intra pubertatem decesserit, tunc Gaius Seius heres mihi esto'.
The substitution of an heir is either double or simple, as for example: 'Let Lucius Titius be my heir: if Lucius Titius will not be my heir, then let Seius be my heir'; 'if he will not be my heir, or if he will be my heir and should die before reaching puberty, then let Gaius Seius be my heir'.
§28.6.1.2Substituere liberis tam heredibus institutis quam exheredatis possumus et tam eum, quem heredem nobis instituimus, quam alterum.
We can substitute for our children, whether they are instituted as heirs or disinherited, and we can substitute either him whom we have instituted as our own heir, or another person.
§28.6.1.3Substituere liberis pater non potest nisi si heredem sibi instituerit: nam sine heredis institutione nihil in testamento scriptum ualet.
A father cannot substitute for his children unless he has instituted an heir for himself; for without the institution of an heir, nothing written in a will is valid.