What are the allowed values and limit of 'Instructions' textarea of a control's property tabsheet?

What are the allowed values and limit of 'Instructions' textarea of a control's property tabsheet?

In Zoho Creator, what are the allowed values and limit of 'Instructions' textarea of a control's property tabsheet? As our test case when I view-sourced and clipped the entire content into the instructions textarea and clicked the OK button the control did not appear at all. Also the 'Edit Field' and similar context menu failed to appear too.

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Deepak Vasudevan
http://thamizhththendral.blogspot.com/