Try this (modified from Cetin code) for testing if the replaced string is being split during FREADs:


#DEFINE MAXBUFFER 65536
lhIn = FOPEN(lcFileIn)
lhOut = FCREATE(lcFileOut)
DO WHILE NOT FEOF(m.lhIn )
lcBuffer = FREAD(m.lhIn, MAXBUFFER)
DO CASE
CASE RIGHT(lcBuffer,3) = 'AD0'
FSEEK(m.lhIn, -3, 1)
lcBuffer = LEFT(lcBuffer,LEN(lcBuffer)-3)
CASE RIGHT(lcBuffer,2) = 'AD'
FSEEK(m.lhIn, -2, 1)
lcBuffer = LEFT(lcBuffer,LEN(lcBuffer)-2)
CASE RIGHT(lcBuffer,1) = 'A'
FSEEK(m.lhIn, -1, 1)
lcBuffer = LEFT(lcBuffer,LEN(lcBuffer)-1)
ENDCASE
FWRITE(m.lhOut,STRTRAN(lcBuffer,'AD00','BR77'),MAXBUFFER)
ENDDO
FCLOSE(m.lhIn)
FCLOSE(m.lhOut)