What do I key in for identification field if the person does not have an NRIC no. equivalent or if I do not have these details?
The identification field is meant to positively identify the person so that there will be no doubt or misidentify who the testator is referring to.
While people typically use their NRIC number (or its equivalent), not all countries employ such a system.
For example, National ID cards in the United Kingdom were abolished in 2011. Hence, individuals are typically identified by other means, including using their National Insurance number, unique driver number, and/or their passport number.
You can use mobile number and/or home address as well though these would be relatively less unique and hence a higher risk of misidentification.
In these cases, under Identification, select “Others” and the country accordingly, and the relevant information accordingly.
Even if the identification details change later (e.g. due to the expiration/renewal of a passport), it does not invalidate the clause in the Will that refers to the individual. However, the individual may need to provide evidence subsequently that they are the person mentioned in the Will. This is why it is better to have accurate information and to update your Will periodically.