Invitation letter: 221(g) green slip at Mumbai

[thetullahoma]

My visa expired last month so came home to get it restamped, but got a 221(g). This time I got a green slip (Mumbai). I have been asked to send an invitation letter among many other documents, but dont know what exactly do they mean by this. This is what the green slip says:

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Scan and submit the following as a pdf document:

* Invitation: An invitation letter from the sponsoring organization in the US. For graduate students, workers, and exchange visitors, this letter should include your supervisor or advisor and details about your work.
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What shall I ask my school to send me?

Thanks

[desi_221]

Any updates on your case please

[thetullahoma]

cleared in 2 weeks

My case cleared in 2 weeks. I came back to the US in mid-Nov after Diwali.