If you want to hide fields from specific users follow the instructions below:
1 - Hit "Customize Form", then click the wrench/screw driver icon next to the field you want to hide.
2 - Once you are on the "Properties" window, click the blue "Data Dictionary" link.
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3 - See the explanation on the image below:
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Note - If you want to hide the field for more than 1 user you can separate the username by a comma with no spaces (WCTRAIN,DLTRAIN,SCTRAIN,ETC)