How to find out which type of fields/placeholder are used in unknown document?

A friend of mine has got a document from a colleague, originally created as .doc (word) document, which contains text areas, light grey background, variable floating size, depening on entered text.

They are used as placeholders (with sample text already filled in, to be overwritten) for to be entered (needed/mandantory) text. When printed, the lightgrey backup is not printed, so you don’t seen them on the paper.

How can I find I find out which LO object type they are? They seems to be some sort of fields, as I can hide the “field shadings”, but I can’t see any field names when switching to “show field names” view mode. They are no form elements. And they’re no function/placeholder. And they’re not fields used for a form letter.

So no real idea, right mouse button etc. does not offer any special menus.

Reason why I’m asking is that unfortunately not all light grey backgrounded areas are of this type, they seems to be somewhat fragile, “destroyed” by user’s mistake, and then they’re printed with grey background. I was asked for help, if I might me possible to “fix” this doc, make it usable within LO. Copy&paste of these “special” fields is not possible, paste looses field attribute.

Any hints where to start are very welcome!


Shortened to minimum sample file: WhatsThis.odt

Did also a save as xml (.fodt), this seems to be relevant line, stripped all from doc except the “mystic field”:

<text:p text:style-name="P17"><field:fieldmark-start text:name="__Fieldmark__26_341087854" field:type="vnd.oasis.opendocument.field.FORMTEXT"><field:param field:name="Description" field:value=""/><field:param field:name="Name" field:value=""/></field:fieldmark-start><text:span text:style-name="T6">mystic_field</text:span><field:fieldmark-end/></text:p>

Seems to be an “unnamed” field.
Leading to my final an most important question: How can I create these “unamed fields” in LO, if some have been “destroyed”/not recognized when converting from .doc/.docx?