This Documentation is written for an experienced programmer.
Sometimes it is nice to fill the PASTE-Buffer from a program to give the user a 
better Function-Key. Or to delete/insert bytes in Ram-Files.
As an example I wrote a General-Update-Program for formatted files. If the user 
deletes a whole entry, the contents is transferred to the Paste Buffer. So the 
delete command is at the same time a copy command. Pressing PASTE brings all the
bytes back through the normal Basic Input.
Making use of the Paste is simple. But you should be aware of:

The use of the CLEAR clears the Paste- Buffer too.

The following little program renames the Hayashi-File as PASTE.DO:

FORL=1TO9:POKE-1626+L,ASC(MID$("PASTE DO+chr$(0)",L)):NEXT

If you execute it once the Paste Buffer can be accessed as the file "PASTE". But
you should only open this file for input or append.
If you open it for output then the Paste-Buffer is killed and reopened using 
another directory entry. If this  happens mostly a cold start is the result of 
pressing PASTE.

But there is a way to empty a file without deleting it. Here is a little set of 
ML subroutines which can be used for searching for the beginning of a file, for 
deleting and inserting a certain amount of bytes, for searching single bytes...

Search for start of File F$  GOSUB 1
Find   A or EOF from Y       GOSUB 2
Delete L Bytes  from X       GOSUB 3
Insert L Bytes  at   X       GOSUB 5


X or Y are adresses in memory
A is an ASCII Value


0 GOTO29
1 FORI=1TOLEN(F$):POKE-878+I,ASC(MID$(F$,I)):NEXT:CALLVARPTR(M(0)),0,VARPTR(X)
:RETURN:REM X=ENTRY from File F$
2 M(39)=VARPTR(M(32)):CALLVARPTR(M(29)),A,VARPTR(Y):RETURN:REM Find A or Filend
3 IFL=0THENRETURNELSEIFL>255THENL1=255:L=L-255:GOSUB4:GOTO3ELSEL1=L+1
4 CALLVARPTR(M(13)),L1,X:RETURN:REM Delete L Bytes beginning with position x
5 IFL=0THENRETURNELSEIFL>255THENL1=255:L=L-255:GOSUB6:GOTO5ELSEL1=L
6 CALLVARPTR(M(10)),L1,X:RETURN:REM Insert L Bytes beginning with position x
29 DEFINTA-Z:DIMX,Y,U,M(39):FORI=0TO38:READP:M(I)=P:NEXT:F$="PASTE.DO"+CHR$(0)
30 FORL=1TO9:POKE-1626+L,ASC(MID$("PASTE DO+chr$(0)",L)):NEXT
31 GOSUB1:REM Find RAM Position of F4
32 Y=X:REM Prepare Y
33 A=26:GOSUB2:REM Find EOF
34 L=Y-X:GOSUB3:REM Empty File F$
37 STOP
70 DATA-27887,-6660,-21555,-11942,-14123,-7219,-11942,29675,29219,201,1615,-
15616,27501,1615,-15616,27551
91 DATA9054,-5290,-14146,-5341,11122,115,9054,-5290,2622,-16194,-5341,11122,-
13965
92 DATA3655,24090,22051,32491,-14152,-14151,29419,29483,8979,-15616


Explanation of the ML-Subroutines:

M(0)  Find Entry of a File
M(10) Insert (File schould not be empty)
M(13) Delete
M(16) IF PEEK(Y)=EOF THEN RETURN
         ELSE Y=Y+1  RETURN
M(22) IF PEEK(Y)=LF  THEN Y=Y+1
         RETURN
M(29) IF PEEK(Y)=EOF THEN RETURN
      IF PEEK(Y)=A   THEN RETURN
      Y=Y+1 : GOTO M(29)

We are selling M100 in Germany with CCITT Modem (Dubbed TELSTAR) and most of the
people get some Software with the Hardware. Last two month they got software 
based on the shown ML-Subroutines. There was no cold start reported, so I think 
they are save.