What are immovables by analogy?

Immovables by analogy are contracts for public works, servitudes, other real rights over immovable property e.g. usufruct and lease of real property for a period of 1 year and registered [especially Par. 10 of Art. 415 of the Civil Code].

[1] The enumeration in Art. 415 is not absolute. Parties may by agreement treat as, but effective only as to them.It is based, partly, upon the principle of estoppel. (Evangelista vs. Alto Surety)

[2] For purposes of taxation, improvements on land are commonly taxed as realty, even though for some purposes, they might be considered as personalty. It is a familiar phenomenon to see things classified as real property for purposes of taxation, which on general principle, might be considered personal property. (Manila Electric v. Central Bank)