Unlike articles, demonstratives are obligatorily produced in their contexts of use in LIS. Demonstratives are pointing signs directed toward a specific point in space and realized with a tense movement (LEXICON 3.6.1).
Demonstratives have a double usage: they can be combined with a noun, and hence function as nominal modifiers (LEXICON 3.6.1), but they can also be used as pronouns (LEXICON 3.7.1). An example of demonstrative functioning as nominal modifier is shown in the discourse stretches below.
wh
A: ix2 buy qartichoke
B: book ix(dem)
โWhat did you buy?โ โThat book.โ
An example of demonstrative functioning as pronoun is shown in the discourse stretches below.
wh
A: ix2 buy qartichoke
โWhat did you buy?โ โThat one.โ
This last example demonstrates that demonstratives can be used in isolation to answer questions.