Answer
Cause
Trap masks are not present. Software can't tell the difference between CT and LW areas of Delta, causing some LW to drop into CT and leave white lines in LW in the same spot.
Solution
If running Delta 5.5 or previous, you must run Delta Trapper to get the mask files. With 6.0 or later, you can generate the masks without actually having or using trapper. Go to the trap tab in the Queue setup and pick "Trap Offline" or "Generate Mask File".

Cause
Extra transparency is on, which deliberately moves some LW/HC elements to the CT to reduce file size. If the lines show up in the LW, but when all are composited and output to film proof they dissappear, this is okay. However, not all systems consuming TIFF/IT files are precise enough to handle this. So if lines show up in the media output, turn off "Extra Transparency" in the Output section of TIFF/ITflow. When in doubt, turn this off. If the TIFF/IT-s are turned back to PS before output (Shira or Harlequin workflows) turn it off.

Answer
Cause
The device consuming the TIFF/IT files does not fully suppport non-integer CT/LW ratios.
Solution
Make sure CT integer ratio function is turned on in the resolution tab in TIFF/ITflow, or in any TIFF/ITflow job ticket you are using.

Answer
General Outline
Step 1. We will use the Delta PrintManager to import in the legacy "Heads-Left" TIFF/IT and convert it to a "Heads-Up" TIFF/IT. This is done with the help of the TIFF/ITflow software.
Step 2. We then use the Delta PrintManager to import in the "Heads-Up" TIFF/IT and make a Heads-Up Delta List.
Step 3. We then use the Delta Transformation tool (Delta 5.5) to rotate the Delta List 90°.

Step 1. Heads-Left to Heads-Up TIFF/IT
I have created a new Delta PrintManager directory queue entitled ROTATE HEAD. Right click on it and slide down to Print TIFF/IT. This will present you with a standard navigation dialog where you locate your source Heads-Left TIFF/IT-s FP file. This queue is also set to run through Delta Trapper so that the resulting TIFF/IT runs smoother.
The queue is set to drop its Delta List in the DeltaFilesForTIFFIT PrintManager export directory.
This DeltaFilesForTIFFIT directory is also a watched hot folder for the TIFF/ITflow software. Do Not launch TIFF/ITflow. It will run as a background service. The TIFF/ITflow software is configured to create a new TIFF/IT from this Delta list in the Head-Up orientation. It does this by spinning the current info 270°

Answer
The TIFF/ITflow software can be set to a single Calibration Curve Text file typically it is the file named calibr.txt.
Inside this file though you may have as many named curves as you want:

CurveName: Intrinsic

0	0
10	12
...
100	100

In this instance the job ticket would refer to this curve using the name "Intrinsic". And each of these curves can be - and usally are - different curves for different purposes.

Then you can create different Job Tickets which use the different curve names in the job ticket to achieve the result you are asking for.

Answer
You can overwrite the existing curves but we don't recommend that.

A better approach would be to copy the curve and then rename it to something that makes sense to you and edit the values.

For instance:
Original Curve in Calibr.txt

CurveName:
Scott Litho					Hammer Press Gain 1					Hammer Press Gain 2
0	0			0	0			0	0
5	3.94			5	3.94			2	1
10	7.99			10	7.99			5	4
20	16.43			20	16.43			10	8
30	25.31			30	25.31			20	17
40	34.64			40	34.64			30	25
50	44.41			50	44.41			40	36
60	54.64			60	54.64			50	46
70	65.31			70	65.31			60	55
80	76.43			80	76.43			70	64
90	87.99			90	87.99			80	77
95	93.94			95	93.94			90	88
100	100			100	100			95	94
								98	97
								100	100

You can also add or remove steps in the curve as you desire.