To understand PO file in detail, open it in Notepad:
On top of the file there is a section called header, where various information are stored. Poedit inserts them via above-mentioned menus. For some languages, it may be necessary to check this header.

Before header, you can insert more detailed info about your project. The lines have to start with character #. Poedit cannot edit this lines.
"Project-Id-Version: 1.0\n"
- you may wish to add a version number
"POT-Creation-Date: \n"
- you may insert the date of first creation (before \n)
"PO-Revision-Date: 2008-11-14 11:36+0100\n"
- automatically created by poedit
"Last-Translator: Renato Pavičić <renato.pavicic-attt-lockonhr.com>\n"
- as in File -> Preferences -> Identity
"Language-Team: Croatian <http://lockonhr.com>\n"
- as in Catalogue -> Settings -> Project info tab
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
- last three to be adapted if necessary
Below header you can see the strings, where msgid contains original text, and msgstr is a placeholder for your translation
Comments in PO filePO files may have some comments that are inserted by program developer, and are intended to tell the translator more about the meaning and usage of the string. This reversal engineering of has no option to extract those comments, as they are not inserted into MO file at all, during it creation.
To view comments in Poedit, go to View menu and choose:
- Show comment window
- Show automatic comments window
I will try to insert as much comments as possible, but if you feel that something is to be commented, post here (under topic related to PO filename), or insert into PO using following option in Poedit:
Choose the desired string, and click Edit comment (notepad icon on a toolbar). Type your comment and click OK. You comment will appear in the lower pane of comments.


Now, open PO in Notepad, and you will see a line like this:

Comments are always inserted with #, and those that precede the string will be shown in Poedit comment window.