1.2.2. Non-manual marking
In LSC definiteness may also be expressed nonmanually. This particular nonmanual consists in squinted eyes [LEXICON 3.6.1]. Importantly, the shared information squinted eyes can co-occur with does not need to be explicitly mentioned in previous discourse, but it can perfectly be accommodated or be part of the shared knowledge between conversation participants. It also indicates that the addressee may retrieve the discourse referent from memory in a long run and serves as a signal to indicate the low accessibility status of the linguistic material that it is aligned with.
Squinted eyes
Moreover, when a determinerless noun phrase is not accompanied by squinted eyes in a context where the discourse referent has not been previously mentioned only the indefinite reading is available.