The phrase "a marker on a" is correct and usable in written English.
It can be used when referring to a specific marker that is placed or located on something, often in contexts related to maps, diagrams, or physical objects.
Example: "The map features a marker on a significant historical site that attracts many tourists."
Alternatives: "a sign on a" or "a label on a".
There are four pools here at Lower Makefield, each one a marker on a suburban child's journey to adulthood: the baby pool; the wading pool, where swimming lessons begin for 3-year-olds; the main pool, where Christie and her friends spend their time; and the lap pool across the way, where the adults get in their swimming time.
As President Barack Obama says, it is a "milestone" – a marker on a longer journey.
The child receives a message saying that the handset's position has been requested, and the parents receive an address, or a marker on a web-based map, giving the child's location.
It is not expected to lead to any new initiative but rather lay down a marker on a longstanding US and international approach to the region before the US president-elect, whose commitment to such a solution is in doubt, assumes office.
This involves the participant following a marker on a 9-point grid with their eyes.
They also extended an image-inpainting algorithm to inpaint a marker on a deformed surface [22].
Right now, however, I just want to lay down a marker on an issue I really really do know something about: America as a net international debtor.
Two independent linkage groups were accepted as linked if a marker on the end of one group showed a cross linkage to another marker on a second group through the " maximum linkages" function of JoinMap 4.0.
Traditional values - notably the Orange Book did not rate a mention - and a marker on Iran.
While unions are 6 of the party's 10 top donors, the bulk of the party's money is coming from corporations and individuals who are motivated both by ideology and an impulse to put down a marker on what might be a winning ticket.
In a case reminiscent of Abu Ghraib, in which guards photographed themselves with Iraqis whom they had posed in humiliating positions, a soldier was censured for writing a mocking slur with a marker on the forehead of a crying detainee.
