Epson S5U1C17001C Manual page 703

GNU17 IDE (5)
Editor Area
The area of the editor where you edit source code. The IDE opens the C editor or the assembler editor according to the file type to be edited.
Error marker
Bookmark marker
Task marker
Marker bar
The marker bar shows the line in error and the markers
indicating a bookmark, a line in which a task is set, etc.
Markers are displayed on the left edge of the
corresponding line.
Editing area
Edit sources in this area.
While a C source being edited, the content assist function
shown below can be used by pressing the [Ctrl] + [Space] keys.
Development Tools
Overview ruler
The overview ruler shows the position in error
and the position at which a bookmark or task is
set by a square symbol. Click a marker to go to
that position.
Reference