Pitman's Commercial Spanish Grammar (2nd ed.)

by C. A. Toledano

(6) On I following U when the I does not form a diphthong, but stands as a separate syllable, as Concluído (concluded), Imbuído (imbued).

(7) On Éste (this), Ése and Aquél (that) when these words are stressed.

[Footnote 4: According to the last edition of the Grammar of the
Spanish Academy, these words may now be written without the accent.]

Crema (Diaeresis).

The diaeresis is placed over u in "güe" and "güi" when the u is to be sounded.[5]

[Footnote 5: In poetry also to divide an ordinary diphthong into two syllables for the sake of rhythm.]

Tilde.

The tilde (~) is used on the letter N to turn it into Ñ, as Mañana (morning) (in old Spanish spelt Mannana).

Notes of Interrogation and Exclamation.

These are used in Spanish both at the beginning and at the end of the question or exclamation, as ¿Qué quiere V.? (what do you want?), ¡Cuántos sufrimientos! (how much suffering!). Note that at the beginning they are reversed.