#CMT# #/CMT# The billboard has a base plate (110) comprising a main cavity (113) receiving a diffusing light slab (140) to retro-light a document. The plate has a secondary cavity (114) receiving an LED display matrix (150) connected to power supply of the plate. A cover covers a face of the plate and includes main and secondary windows corresponding to display surfaces formed by the slab and matrix. Magnetic studs (115) removably fix the cover at surface of the plate. A transmission unit has an interface complementary to a communication interface (151) of the matrix to transmit display data to the matrix. #CMT#USE : #/CMT# Light billboard for use in real estate agencies for displaying real estate products for sale or rent. #CMT#ADVANTAGE : #/CMT# The billboard allows variable, partial display of information to attract attention of observer or passerby on a special character of the information displayed by the bill board as the billboard is used in combination with number of billboards covering a surface of a showcase. The billboard enables adapting or modifying the information displayed by the billboard without a need to modify the display itself while maintaining the attraction of information display mode. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a front view of a base plate of a light billboard provided with diffusing light slab and diode display matrix. 110 : Base plate 113 : Main cavity 114 : Secondary cavity 115 : Magnetic studs 140 : Diffusing light slab 150 : LED display matrix 151 : Communication interface.