Native File Resize {R}←X ⎕NRESIZE Y

This function changes the size of a native file.

Y is a negative integer tie number associated with a tied native file.

X is a single integer value that specifies the new size of the file in bytes. If X is smaller than the current file size, the file is truncated. If X is larger than the current file size, the file is extended and the value of additional bytes is undefined.

The shy result of ⎕NRESIZE is the tie number of the resized file.