On Friday, August 4, and Saturday, August 5, 2023, a celebratory postmark will be in use at post office 5101 Nova Gorica. The postmarks are intended to commemorate The 20th World Lace Congress and General Assembly of The International Bobbin and Needle Lace Organisation OIDFA 2023. The OIDFA Congress is the largest and most important lace event in the world, which this time is hosted by the cities of Nova Gorica in Slovenia and Gorica in Italy. The Philatelic Society of Maribor and the Philatelic Society of Nova Gorica prepared, in addition to special postmark, a joint special cover (PS Maribor no. 226/2023 and PS Nova Gorica no.: 202/2023) as well as a lace philatelic exhibition and an exhibition of social issues. The lace patterns for the motifs in the postmark were contributed by pattern designers Irma Pervanja and Simona Strgulc Krajšek. The postmark was designed by philatelist Mitja Jančar. The philatelic exhibition will be on display in the premises of the Municipality of Nova Gorica from July 29 to August 11, 2023, from Monday to Friday from 8 a.m. to 3 p.m.