Radio Shack TRS-80 Model II Reference Manual page 221

Technical Information
CLOSE
(function code 42)
This routine terminates access to the file.
If
there are records in the Buffer
Area not yet written, they will be written at this time.
Entry Conditions
(DE)
=
Data Control Block for currently Open file
A= 42
Exit Conditions
NZ => Error
A
=
Error Code
Upon return, the filespec (except for the password) will be put back into the
DCB.
WRITNX
Write Next Record (function code 43)
This routine writes the next record after the last record accessed; that is, it
writes sequentially.
IfWRITNX
is the first access after the file is Opened, the
first record will be written.
Entry Conditions
(DE) = Data Control Block for currently Open file
HL
=
Reserved for use in later versions
OfTRSDOS
A
=
43
Before calling
WRITNX,
put your record in the record area pointed to by
RECADR
in the Parameter List, or, if
RL=256
and record type is Fixed, your
record is in the area pointed to by
BUFADR.
Exit Conditions
NZ = Error
A
=
Error Code
257