It is to convert scale variables/ parameters to string or back to numeric type. This is very tricky, if the notation is not metric, but the imeprial one, which is used in USA.

The solution is a simple case detection with string operations. See also the table for GLOB_SCALE.

!»» Example with automatic scale string of drawing stamps
scaleS=AC_DrawingScale

!»» CONVERT SCALE-STRING TO NUMERIC
scaleN=0
!»» Cut of "M" at the beginning. Not needed.
s=STRSTR(scaleS,"M")
IF s THEN scaleS=STRSUB(scaleS,s+1,STRLEN(scaleS)-s)
!»» Imperial or metric?
s=STRSTR(scaleS,"=")
!»» Converting ...
IF s THEN
  !»» Scale notation is imperial
  sts=SPLIT(STRSUB(scaleS,1,s-1),"%n",lengthR)
  sts=SPLIT(STRSUB(scaleS,s+1,STRLEN(scaleS)-s),"%n",lengthP)
  IF lengthR THEN scaleN=lengthP/lengthR ELSE scaleN=MAX(lengthP,0)
  ELSE
  !»» Scale notation is metric
  s=STRSTR((scaleS,":")
  IF s THEN
    sts=SPLIT(STRSUB(scaleS,1,s-1),"%n",lengthR)
    sts=SPLIT(STRSUB(scaleS,s+1,STRLEN(scaleS)-s),"%n",lengthP)
    IF lengthR THEN scaleN=lengthP/lengthR ELSE scaleN=MAX(lengthP,0)
    ELSE
    sts=SPLIT(scaleS,"%n",scaleN)
    ENDIF
  ENDIF
!»» scaleN contains the divisor of the scale.

!»» PRINT RESULTS
TEXT2 0,0,"»"+scaleS+"« - »"+STR("%^.3",scaleN)+"«"

!»» Example with project scale
scaleN=GLOB_SCALE

!»» CONVERT NUMERIC TO IMPERIAL NOTATION
IF scaleN<2000 AND NOT(scaleN>=100 AND FRA(scaleN/10)<0.001 ) THEN
  scaleI=STR("%^.128fi",1" * 12/scaleN)+´=1'0"´
  ELSE
  scaleI=´1"=´+STR("%^.32ffi",scaleN*1")
  ENDIF
!»» scaleI contains the imperial scale string.

!»» PRINT RESULTS
TEXT2 0,0,"»"+STR("%.3",scaleN)+"«  -  »"+scaleI+"«"

!»» Example with project scale
scaleN=GLOB_SCALE

!»» CONVERT NUMERIC TO METRIC NOTATION
praefix="M "
IF scaleN<1 THEN
  scaleM=praefix+STR("%^.0m",1/scaleN)+":1"
  ELSE
  scaleM=praefix+"1:"+STR("%^.0m",scaleN)
  ENDIF
!»» scaleM contains the metric scale string.

!»» PRINT RESULTS
TEXT2 0,0,"»"+STR("%.3",scaleN)+"«  -  »"+scaleM+"«"