| Subject | English | Welsh |
| comp., MS | header row | rhes pennyn (The first row in a spreadsheet. The header row contains category labels that describe the contents of the columns) |
| comp., MS | header source | ffynhonnell pennyn (A document that contains the header row (or header record) to be used with the data source specified for a mail-merge main document) |
| comp., MS | message header | pennawd neges (A hidden section of an e-mail message. From the time a message is first created, information about it is added to the message header, including technical details, such as who created the message and the software used to compose it) |
| comp., MS | P2 header | Pennyn T2 (A hidden section of an e-mail message. From the time a message is first created, information about it is added to the message header, including technical details, such as who created the message and the software used to compose it) |
| comp., MS | page header | pennawd tudalen (One or more identifying lines printed at the top of a page. A header may contain a page number, a date, the author's name, and the document title, the name of chapter) |