Per 
Item #: SCP-S15
Object Class: Safe
Special Containment Procedures: SCP-999 is to help the Linguistics department with work on this language. They are tasked with making a dictionary so everyone can read. MTF-Sigma-1 ("Sculpture Readings") is spreading knowledge of SCP-S15 to as many people as possible. Research on SCP-000 is also underway because of SCP-S15-1.
Description: SCP-S15 is a written language similar to a combination of Ainu and Greek. It has an antimemetic property so that only SCP objects with Item Numbers less than 1000 can understand it. Temporary redesignation seems to counter the effect (See Test 3). Joke SCP objects cannot read it, regardless if the designation is less than 1000 (See Test 4).
Discovery: SCP-S15 was discovered in a cave in Norway. Researcher Serii and SCP-131-A found a stone inscription with writing in SCP-S15, classified as SCP-S15-1. It seems to be dated January 1st 1875. Researcher Serii was unable to read it but SCP-131-A was. It was taken to Site-19 where the Linguistics department failed to read it. However, Dr Bright, being SCP-963, as able to read it and was able to translate the inscription. A transcription is provided below.
Hello, SCP objects. This is the Administrator. There is something more dangerous than SCP-001:O5. I classified it as SCP-000. It is a threat to the entire world. I trapped it in a pocket universe, but given enough time, it will break its way free. Its only weakness is this language. In order to defeat it, everyone must be fluent in this language. But so far, due to a glitch, it can only be understood by the SCP objects under SCP-1000. I believe this is the result of SCP-000, clearly trying to get in our way. So please, spread the word.
MTF-Sigma-1 ("Sculpture Readings") was formed with the main goal being to get the entire population to be fluent in SCP-S15.
Test 1
Subject: D-S15-1, inflicted with SCP-868
Results: Able to read the text.
Test 2
Subject: SCP-2389, switching Item numbers with SCP-389
Results: Able to read the text. When the message was transcribe in its original language and put it in SCP-389, the replier was unable to translate it. Both reclassified to original designations. Another message asking to translate the message again resulted in the replier translating it sucessfully.
Test 3
Subject: D-S15-2, who drunk "A cup of the ability to translate SCP-S15" requested from SCP-294
Results: Able to read the text.
Test 4
Subject: SCP-184-J
Results: SCP-184-J, the squirrel that makes you keep on talking and elaborating on what you say, possessed an inablility to read, understand or translate the stone inscription which is called SCP-S15-1, as it is written in SCP-S15, a language that can only be read, understood and translated by Series I SCP objects, which are SCP objects(Anomalous objects classified by the SCP Foundation) which possess Item numbers less than 1000. Thus joke SCP objects possessing three digit item numbers, Series I SCP objects, possesses the inability to read, understand or translate sentences written in SCP-S15, as they are not part of Series I.
"Sorry." - Writing Researcher Anjeez929
Test 5
Subject: SCP-191
Results: SCP-191 was tasked to guess more words of SCP-S15 using SCP-S15-1. O5-1 was brought in and was asked if SCP-191's output is correct. Even though she confirmed she understands the language, SCP-191 got 23 correct out of the 100 words given, since most of it was guessing.
Test 6
Subject: D-S15-3, standing in SCP-233's safezone
Results: Able to read the text
Test 7
Subject: D-S15-2 (See Test 3) and D-S15-4, who also requested "A cup of the ability to translate SCP-S15" from SCP-294. Both are to enter the 800m radius of SCP-1643.
Results: The 800m radius was cleared out of people and D-S15-2 and D-S15-4 were brought in. Both were still able to understand SCP-S15, even though the two D classes were able to understand at least one other language.
"Well that's convenient" - Researcher Rosen
