Text Translations for the custom ME21N transaction in PT language

Hi,

We have the requirement to translate the custom T code Zme21n (copy of Std. ME21N tcode) in PT language.

we have maintain the translations for all the screens and menu.

In Document overview screen, which appears at the left hand side when we click the "document overview on" button on the toolbar, we are unable to translate the context menu used to select the purchase order or other documents to copy.

We tried to find out the technical details for that screen but there is no information available. We have already translated all the screens, interfaces and toolbar for the tcode using se63.

we are not able to find the place where this menu text is maintain.

Please provide any help regarding the same.