Tractum was a Roman flat bread used as a thickener in dishes, rather than as a bread in its own right.
It was made from raw dough rolled out into round discs, and let dry naturally.
It was then crumbled as a thickener into sauces, soups, stews. Had it been cooked first, it couldn’t have been used as a thickener.
Tractum could also be used whole in dishes: it was often brushed with oil, and used in layers in a dish as you would wide flat pasta noodles.
But otherwise, it does not seem to have been meant to be used as a Roman form of pasta. You wouldn’t boil it, and expect it to stay whole.
Nor from the texts extant mentioning it, does it seem to have been meant as a type of bread you would eat on its own, at the table.
The use of tractum as a thickener may have evolved into the Medieval practice of using bread crumbs to thicken sauces with.
Literature & Lore
The cookbook writer Apicius mentions tractum’s use as a thickener.
“Pultes tractogalatae: lactis sextarium et aquae modicum mittes in caccabo novo et lento igni ferveat. Tres orbiculos tractae siccas et confringis et partibus in lac summittis. Ne uratur, aquam miscendo agitabis. Cum cocta fuerit, ut est, super ignem, mittis melle. Ex musteis cum lacte similiter facies, salem et oleum minus mittis.”  Apicii de re coquinaria. V Ospreos. I. PULTES: 3.http://www.hs-augsburg.de/~harsch/Chronologia/Lspost04/Apicius/api_re00.html
“Put a pint of milk and some water in a new clean pot; break dry bread (tractum) into it, stir well over a slow fire to prevent burning; add water as necessary. Honey and mead are treated similarly, mixed with milk, with the addition of salt and a little oil.”
“Trahere” in Latin means to drag or pull. One form of the verb is “tractum.” Our English word “tractor” comes from this.
Trahere could also have a sense of meaning “cast.” When Caesar crossed the Rubicon in January 49 BC and said “The dice is cast!”, what he actually said in Latin was “Dadum tractum est!”
The plural of tractum is tracta.
|↑1||Apicii de re coquinaria. V Ospreos. I. PULTES: 3.http://www.hs-augsburg.de/~harsch/Chronologia/Lspost04/Apicius/api_re00.html|