Cryptonym: GR
https://www.archives.gov/files/iwg/declassified-records/rg-263-cia-records/second-release-lexicon.pdf
CIA document: Research Aid: Cryptonyms and Terms in Declassified CIA Files Nazi War Crimes and Japanese Imperial Government Records Disclosure Acts: Pages 29-31 contain a number of cryptonyms with the digraph GR.
104-10169-10343: DISPATCH-TRANSMITTAL OF CLANDESTINE PHOTOGRAPHS TAKEN DURING MAY 1955.
08/18/55: Dispatch from Chief of Base, Vienna to Chief, EE (Attn: Silvan A. Hobson): Subject: General - Operational/GREPIC. Specific - Transmittal of GRATONIC-1 Clandestine Photographs Taken During May 1955: "1. Transmittal herewith are 407 clandestine photographs taken by GRATONIC-1 during the month of May 1955. All of them were taken with the 'chest camera' described in the reference and previous correspondence. The numbering system is the same as and a direct continuation of that used for the initial GRATONIC-1 photographs transmitted with the reference...At the present time, GRATONIC-1 coverage of sensitive areas is being temporarily suspended, both in order to avoid burning him through overuse and because the VCB Technical Support Section, in the midst of its move from GRATLAS (Vienna Operations Base in Stiftsdaserne) to GRBAIL, is not able to process photographs..."
104-10172-10111: HALPERIN, MAURICE HYMAN.
11/22/58: Cable from REDACTED to Director: Slugline GROOVY GRENGULF: "1. GRENGULF (Austrian State Police) reports that a Morice (sic) Halpin (note: Maurice Halperin) DPB 3 March 1906 and his wife Edith, nee Frisch, DOB 6 July 1907, both carrying US passports, entered Austria from Suisse on 10 Nov 1958. Passports had Czech visas. According GRENGULF, this couple reportedly belong to circle of acquaintances of atom spy Klaus Fuchs and during their stay in Suisse were under close surveillance." Handwritten: 201-128561. Slugline GROOVY GRENGULF also on a 11/24/58 memo at p. 129: "Chief of Station comment: Action responsibility for this cable has been transferred from EE to WH by Mr. REDACTED EE ext 8473, in coordination with Mr. REDACTED WH ext 2555." At p. 33, 1/19/61: "Maurice Halperin, former OSS officer Latin American affairs specialist, and Martha Dodd Stern, former resident Mexico, both previously implicated Soviet espionage in (USA). Both now in Bloc...Pass above to TIEBAR-8." At p. 7, Halperin's 1961 book "Dessarollo Economica y Crisis en la America Latina."
https://www.cia.gov/readingroom/docs/GRCROOND%20GRREPAIR%20%20%20VOL.%204%20%20%28GRCROOND%20OPERATIONS%29_0007.pdf
07/10/59: Cable from Vienna to Director: Slugline KAPOK GROOVY GRCROOND: RE VIEN 5433 (IN 39035): "Request traces and POA for contact, recruitment as short-term stay-behind spotted for GRCROOND. IDEN was investigator for CIC in Linz and was USEP investigator in VIEN until recent cutback, was Afrika Korp radio operator in World War II. No derog info VIEN or GRBANAL files." - - - "GRCROOND Project involved staybehind paramilitary operations in Austria to develop escape and evasion network. GRREPAIR Project developed the central section of the escape and evasion network in Austria. Egbert Hochhauser, Hans Tschurtscenthaler considered for possible use on Project GRCROOND." See page 30 of this document: https://www.archives.gov/files/iwg/declassified-records/rg-263-cia-records/second-release-lexicon.pdf