Where the significator of the questited is located in the house of the querent. This gives a promise of perfection but usually needs supporting factors to reinforce the promise, (as explained below).
Lilly writes of emplacement (CA., p.126 - 127)
Things are sometimes perfected by the dwelling of Planets in houses, viz., when the Significator of the thing demanded is casually posited in the Ascendant; as if one demand if he shall obtain such a Place or Dignity, if then the Lord of the tenth be placed in the Ascendant, he shall obtain the Benefit, Office, Place or Honor desired. This rule of the Ancients holds not true, or is consentanious to reason, except they will admit, that when the Moon, besides this dwelling in house, doth transfer the light of the Significator of the thing desired, to the Lord of the Ascendant; for it was well observed that the application of the Significators shew inclination of the parties, but separation usually privation; that is, in more plain termes, when you see the principall Significators of the Querent, and the thing or party quesited after separated, there's then little hopes of the effecting of perfecting what is desired (not withstanding this dwelling in houses) but if there be application, the parties seem willing, and the matter is yet kept on foot, and there is great probability of perfecting it, or that things will come to a further treaty.