The 18 main guardie of the Dardi School can actually be broken into 5 family types. Those family types are the Coda Lunga family (4 guardie), the Porta di Ferro family (6 guardie), the Braccio family (2 guardie), the Extended family (2 guardie) and the High family (4 guardie).
There are a couple of supplementary named guardia positions, however these are essentially positions you pass through. Guardia Fianca & ponta di terro are two examples.
We also have some commonly used modifying descriptors for the Coda Lunga and Porta di Ferro families, that being stretta (narrow), larga (wide) and alta (high / open), which in turn relates to sword positioning. Stretta guardie are those in which the point is up, larga are those in which the point is held down, and alta is that in which the sword hand is held higher than usual.
The Coda Lunga Guardie
The Coda Lunga (Long Tail) Guardie take their name from the Guardia di Coda Lunga Distesa, which has the blade held extending behind the fencer like a tail. The unifying characteristic of all these guardie is that the sword is held with the hand in third in second. This is a very natural conformation of the hand and sword arm. Coda Lunga Alta, whilst sometimes having the hand slightly higher than usual, specifically refers to the sword up buckler foot forward stance, which appears to be named for it’s high sword position in relation to Coda Lunga Distesa. Manciolino only describes the Coda Lunga Stretta and Coda Lunga Alta guardie, with a reference to Coda Lunga Larga.
The Porta di Ferro Guardie
The Porta di Ferro (Iron Gate) guardie have the unifying characteristic that the hand is held in third. The stretta and larga guardie are held at navel height, and the alta guardia is held at shoulder height. The base Porta di Ferro guardie are taken with the sword foot forward, and when the buckler foot is held forward this is differentiated as Cingiara Porta di Ferro (Boars Iron Gate). Manciolino only describes the Porta di Ferro Stretta, Porta di Ferro Larga and Cingiara Porta di Ferro (assumed to be Stretta) guardie.
The Braccio Guardie
The Braccio (Arm) guardie have the unifying characteristic that the hand is next to the buckler hand with the blade pointing behind the body. Sopra il Braccio is held with the blade above the buckler forearm, and Sotto il Braccio is held with the blade below the buckler forearm.
The Extended Guardie
The Extended guardie have the unifying characteristic that the hand is held with the blade completely extended and pointing forward to thrust / threaten the enemy. Intrare is held with the hand in 3rd, and Faccia is held with the hand in fourth. Manciolino only utilises Faccia to describe any guardia that points at the face, and the hand is therefore assumed to be in an appropriate position from third through to fourth.
The Raised Guardie
The Raised guardie have the unifying characteristic that the hand is held above the shoulder to form the guardia. There are 2 guardie with the point hanging down, and 2 guardie with the point up. Beca Cesa (right leg forward) and Beca Possa (left leg forward) are the hanging guardie, with the hand held above the head in 1st, and the sword sloping down and across the line of the body, the point threatening the enemy. Guardia di Testa is held with the sword pointing forwards and up at 45° to defend the head, either foot may be forward. Guardia Alta is held with the sword held directly above the body with the hand in 3rd, feet typically are in narrow measure. Manciolino only describes the Testa and Alta guardie, with a reference to Beca Cesa, which he describes as Guardia d’Alicorno.