The rules that use the category "<det-sing-indef>" are:

<discourse_det-not_wh-sing>

<det-sing-indef>

<discourse_det-sing>

<det-sing-indef>

<discourse_det-not_wh_or_gq_or_dummy-sing>

<det-sing-indef>

<discourse_det-indef-sing>

<det-sing-indef>