Gurmukh with Sihari

I have discovered Sikhi very recently and in my free time I try to learn Gurmukhi. There are no Sikhs in my country so I learn on my own, with what’s available on the web. I was reading the second Pauri of Jap Ji Sahib and I saw that the word Hukam has 3 different forms: ਹੁਕਮੀ, ਹੁਕਮੁ, ਹੁਕਮੈ. (https://www.reddit.com/r/Sikh/comments/2xplia/jap_ji_sahib_analysis_of_pauri_2_hukam_wahegurus/)

I think that the word changes depending on “case”. I just searched Cases in Punjabi Grammar and I found this:

Punjabi distinguishes two genders, two numbers, and five cases of direct, oblique, vocative, ablative, and locative/instrumental.

(http://shodhganga.inflibnet.ac.in/bitstream/10603/4456/11/11_chapter%203.pdf)

/r/Sikh Thread