Landa means alphabet "without tail", implying that the script did not have vowel symbols.
The usage of Gurmukhī letters in Guru Granth Sahib meant that the script developed its own orthographical rules.
In the following epochs, Gurmukhī became the prime script applied for literary writings of the Sikhs.
According to al-Biruni, Ardhanagari was a mixture of devanagari used in Ujjain and Malwa and Siddha Matrika or the last stage of Siddhaṃ script, a variant of the Śāradā script used in Kashmir.
This theory is confusing as Gurmukhī characters have a very close resemblance with "Siddh Matrika" inscriptions found at some sacred wells in Punjab as G.
The Laṇḍā scripts were used for household and trade purposes.