[Guide] Creating Building Instructions using LPub

[Kristel]

Guide: create build instructions with LPub

This is a guide to making your own instructions with LPub. There is a:

1. Short Guide
   Walks through the basics of producing a set of instructions.
   
2. Full Guide
   Provides more details on the main steps for making instructions and explains the main features of LPub.
   
3. User's discussion
   You are encouraged to ask questions, provide constructive criticisms and suggest proposals to improve this guide and suit it to users' needs.
   This guide will be updated over time to reflect the frequently asked questions.
   

A complete guide to using LPub can be found here.

List of recent topics that are related with LPub and build instructions:

• Instruction Miner vs. LPub (-> Go)
  
• MLCad: hiding parts in instruction step but showing in BOM (-> Go)
  
• LPub and MPD Files (-> Go)
  
• Help to create digital instructions for a physical MOC (-> Go)
  
• LPub not showing my main assembly (-> Go)
  
• Better building instructions than LDD? (-> Go)
  
• Problem with MLCad and Lpub (-> Go)
  
• LPub tree step - how? (-> Go)
  
• ...
  

Credits

- Thanks to Kevin Clague, the creator of LPub.

- Thanks to Jaco van der Molen for his complete LPub guide.

Note: This guide was prepared using a Mac. There may be minor differences for the Windows version of LPub.

[Kristel]

Short Guide to LPub

This is a brief guide that will allow you to produce a set of instructions with minimum fuss (but also minimal formatting). Each subheading below is linked to the relevant section in the full guide where you can find more information and more options.

1. Getting Started

Before you can use LPub, it is critical that you have the LDraw parts library and a rendering engine (LDGLite or LDView) installed and and have told LPub where on your computer these files are located.

Open your file by clicking on the folder icon at the top left of the canvas or going through the File -> Open menu.

2. Formatting the Instructions

Once your file is open, the first step is to set the formatting for the instructions as a whole. These formatting settings are found in the Page Setup, Assembly Setup and Parts List Setup in the Configuration menu.

LPub defaults to a portrait A4 page (American standard). If you need to change this to suit your model, you can do so in the Page Globals Setup window, found under Configuration -> Page Setup menu.

In the above example, I have set the size of the paper to 21.0cm x 29.7cm, which is the Australian A4 standard in portrait. It's also a good idea to increase the margins to 0.25 as this spreads the elements on the page out a little more and makes them look less crowded.

LPub defaults to a scale of 1.0 for the assembly image, which may need to be reduced to fit a large model on the page. You can do this in the Assembly Globals Setup window, which is found under the Configuration -> Assembly Setup menu.

3. Formatting Individual Steps

The next step is to use the navigation arrows at the top of window to go through each page of the instructions, and apply local formatting as required.

Depending on the parts and the size of the assembly image, the assembly and parts list sometimes overlap.

• You can move the assembly image by clicking on it, holding the mouse button down and dragging the image to another location on the page.
  
• LPub commonly displays the parts list in a portrait format. You can change the shape of the parts list by clicking on it to bring up the bounding box with a little black square. Click on this black square, hold the mouse button down and then drag it up or down to change the shape.
  

Large parts (for example, a baseplate) can be excluded from the parts list and the Bill of Materials as follows:

1. Locate the parts in the code. This can usually be identified by the part number (e.g. "3857.dat" for a 16x32 baseplate).
   
2. Add the LPub code shown below before and after that part.
   
3. Refreshing the image by clicking the clockwise arrow at the top of the code window.
   

0 !LPUB PLI BEGIN IGN
1 10 0 8 160 0 0 1 0 1 0 -1 0 0 3857.dat
0 !LPUB PLI END

If you can't see the code window, you can activate it through the View menu.

The ROTSTEP command can be used to rotate the assembly image to give a better view of where a part needs to be added. This command is added at the start of the step that needs to rotated and takes the following form:

0 LPUB ROTSTEP X Y Z REL

Where X, Y and Z specify the values for how far (in degrees) the assembly should rotate around each axis. For example, the following code will rotate the assembly 90 degrees around the Y-axis:

0 LPUB ROTSTEP 0 90 0 REL

Once a rotation has been set, it will apply to all subsequent steps. You can set the view back to the original orientation by adding the following code to the step where you need the original orientation to be shown:

0 LPUB ROTSTEP 0 0 0 REL

4. Grouped Steps and Submodels

If you have a submodel (shown with a light yellow background as the default formatting), you can group the steps as follows:

1. Right-click on the page to bring up the pop-up menu.

2. Select "Add Next Step".

3. Repeat steps 1 & 2 until you have all the steps for the submodel on the page.

Don't worry if all the steps don't fit on the one page. You can continue the steps on the next page.

You can also convert a submodel to a callout by right-clicking on the page to get the pop-up menu and selecting "Convert to Callout". Callouts are not recommended where the submodel consists of more than 5 steps or for large submodels as it becomes difficult to fit and format on the page.

5. Bill of Materials

You can add a Bill of Materials at the back of the instructions as follows:

1. Navigate to the last step.

2. Add a page by selecting "Append Page" in the Edit Menu.

3. Selecting "Add Bill of Materials", which is also under the Edit menu.

4. Add the last line shown in the following code box (the first two lines are added automatically through steps 2 & 3):

0 !LPUB INSERT PAGE
0 !LPUB INSERT BOM
0 !LPUB BOM SORT FALSE

If the Bill of Materials is too large to fit on the page, reduce the scale of the BOM contents. This can be done in the "Contents" tab of the Bill of Materials Setup window, which is accessed from the Configuration -> Bill of Materials Setup menu.

6. Exporting the Instructions

You can add a cover page at the beginning of the instructions as follows:

• Insert a blank page by choosing "Insert Cover Page from the Edit menu.
  
• Navigate to the front page.
  
• Add an image by choosing "Add Image", which is also in the Edit menu.
  
• Reposition and resize the image as required.
  

Note: This assumes you have an image that you want to use as a cover page. This is generally the easiest way to generate a quick cover page for the instructions.

Once you're happy with the layout of the instructions, you can export them to a PDF by clicking on the PDF icon.

[Kristel]

Full Guide to LPub

This is a more detailed guide to producing instructions using LPub. It covers:

1. Getting Started
   Prerequisite programs that need to be installed, as well as opening and saving files.
   
2. Formatting the Instructions
   Formatting options for the instructions as a whole, such as page orientation, borders, fonts, colours and scale of images.
   
3. Formatting Individual Steps
   Formatting options for individual steps, such as placement of the assembly image and parts list,changing the scale of the assembly image, rotating the assembly image and excluding parts from the parts list.
   
4. Submodels and Grouped Steps
   Creating and laying out grouped steps and callouts, including how to use callouts to highlight difficult to see parts.
   
5. Adding the Bill of Materials
   How to add a BOM and formatting options to fit it on one page.
   
6. Exporting the Instructions
   Adding a cover page and image, and then getting the instructions out of LPub into a readable format.
   

[Kristel]

1. Getting Started

1.1 What you need to have installed

Before you can use LPub, it is critical that you have both the LDraw parts library and a rendering engine installed, and that you tell LPub where they are installed on your computer. This is done in the Preferences sub-menu, under the “LPub” menu.

As shown in the image below, LPub requires you to have LDGLite or LDView installed.

The LDraw library can be downloaded from here:

http://www.ldraw.org...ts/latest-parts

Link to LDGLite:

http://ldglite.sourceforge.net

Link to LDView:

http://ldview.sourceforge.net

1.2 Opening the File

When you open LPub, it will start with a blank canvas. You can open you file by clicking on the folder icon at the top left and then navigating to your file.

Tips:

1. Save your file with a different filename at this stage to preserve the original model (just in case you make a mess - trust me, this can happen).
   
2. Always use the "File Save As" option rather than making copies of your file in the file browser. I'm not sure if this is a Mac only issue, but copying the file in your file browser can result in multiple copies of the model within the one file.
   

[Kristel]

2. Formatting the Instructions

The "Configuration" menu is the starting point for setting the overall formatting of the instructions. Any changes to the setting made here will apply to the document as a whole.

2.1 Page setup

Use this menu to set the width and height of your page. In the example below it is set to 29.7 cm wide and 21.0 cm high, which is the standard A4 page (in Australia at least) in landscape mode.

You can also use this menu to change the background colour and add a border to your pages. If you add a border, you will also need to increase the margins for the page number and step number to avoid the border overlapping the page and step numbers. The margin will need to be slightly greater than the width of the border. For example, if you set the width of the border to 0.5, the page and step margins should be set to 0.6 or more.

The page number margin is set in the "Page Number" tab in the "Page Globals Set" window shown above. For the step number, the margin is set in the Parts List Setup window (see Section 2.3 below).

Hint: Adding colour and borders can have a significant impact on the overall size (in megabytes) of the finished instructions.

2.2 Assembly Setup

The most important parameter in this menu is the scale of the model. I try to keep it between 0.8 and 1.0 wherever possible as reducing the scale below 0.8 can make it difficult to see the detail in the model and identify the new parts added to the step.

Hint: You can change the scale of the assembly on an individual page by right-clicking the assembly and choosing “Change Scale”. Just make sure you say “Yes” to only changing the scale for that particular step (if asked), or it will be applied to all your steps.

2.3 Parts List Setup

This is the format menu for the list of parts for each individual step. You can change the size of the parts shown by reducing the scale, which can be useful if you have steps that have a large number of parts. However, the more you reduce the scale, the harder it can be to identify the individual parts.

If you have a relatively simple model, you can also choose to exclude the parts list from each step, by unchecking the box highlighted below.

Other formatting options for the parts list include background colour, border and font size. See here.

2.4 Bill of Materials Setup

This gives the options for formatting the Bill of Materials (BOM), which is the full list of parts used in the model. See Section 5 for more information on the BOM.

2.5 Callout Setup

The Callout Setup gives you the formatting options for submodels that are shown as a group of steps with the main model.

The divider can be used to put the individual steps into columns or rows, enabling you to put more steps within the callout. The key parameter for the divider is the margins, which I normally set to "0.5". If this is too low, the steps can look cluttered.

See Section 4 for more information on how to use dividers.

The other key option is whether to have the parts shown for each step, which is found on the second tab of the Callout Setup window. You can reduce the size of the callout by unchecking this box. However, if you have a large number of parts for the submodel, it may make sense to show them at each step.

2.6 Step Group Setup

The Step Group Setup gives you the formatting options where two or more steps are shown as a series of steps on a page (but not as a callout). You can specify the margins (i.e. space between parts, dividers and assemblies), whether to include the parts list per step and the font for the step number.

The background colour for the Step Group defaults to light yellow (similar to official instructions). You can change this on the Page Setup menu.

2.7 Project Setup

The only parameter you can set here is the resolution (in dots per inch or cm).

[Kristel]

3. Formatting Individual Steps

Most of the individual items on a page can be tailored by selecting the object and moving it and / or resizing it, or by right-clicking the object to get the pop-up menu of options. This section covers some of the commonly used edits.

3.1 Moving the Assembly Image

You can move the assembly image by clicking on it, holding down the mouse button and dragging it to another location on the page. This is useful if you have a large parts list that cuts across the assembly model and for making room for a callout on a page.

3.2 Changing the Shape of the Parts List

You can change the shape of the parts list as follows:

1. Click on the box to bring up the outline with the little black square.

2. Click and hold the black square and move it up or down to achieve the desired shape.

3.3 Changing the Size of the Assembly Image

You can change the size of the assembly image as follows:

1. Right-click the assembly to bring up the pop-up menu.

2. Choose "Change Scale".

3. Enter the required scale and click "OK".

Note: If you are asked whether to apply this to only this step, click "Yes", else the change in scale will apply to all steps.

3.4 Excluding Specific Parts from the Parts List

Large parts, such as baseplates, can make the parts list look rather messy and also reduces the space available for the full Bill of Materials. You can reduce the scale of the parts, but this affects all parts and you can only reduce the scale so far before the smaller parts become difficult to recognise.

You can hide a specific part from the parts list for the step and the Bill of Materials by:

1. Locating the part you want to hide (Hint: look for the part number).

2. Adding the following LPub code before and after the code for the part you want to hide:

0 !LPUB PLI BEGIN IGN
1 10 0 8 160 0 0 1 0 1 0 -1 0 0 3857.dat
0 !LPUB PLI END

3. Clicking the "Redraw" icon to refresh the image.

See here for the before and after screenshot.

3.5 Substituting single parts for one part

Sometimes it is necessary to convert two or more parts into a single part. For example, leg assemblies used in MLCad's minifigure generator show up in LPub as the individual parts that make up the legs (i.e. left leg, right leg and hips), as shown in the image below. PLI SUB commands within LPub can be used to show the complete leg assembly in the parts list.

The first step to convert the three parts into a single part is to find the part number. In this particular example, part number 82059 was used to create the legs in the MLCad minifgure generator was 82059, which means the file for that part will be called "82059.dat".

The next step is to add the following code in LPub:

0 !LPUB PLI BEGIN SUB 82059.dat
0 !LPUB PART BEGIN IGN
1 [... parts that are being substituted out]
0 !LPUB PART END
0 !LPUB PLI END 

The first command tells LPub what part to substitute in and the second command line tells LPub to start the substitution. These two lines are added before the code for the parts that are being substituted out. The last two commands are added to tell LPub to stop the substitution process.

The final step is to press the "Redraw" icon at the top of the Lpub control file. As shown below, the three leg elements have now been replaced with the single part.

Note: Credit to Alasdair Ryan for providing the content for this section.

3.6 Incorporating LSynth parts

LSynth allows you to incorporate and render flexible elements, such as hoses, pneumatic tubing and power function cables, into your model and instructions.

The code for LSynth parts is mainly added in MLCad and is therefore not covered in this guide. However, Alasdair Ryan has written a comprehensive tutorial on incorporating LSynth parts. His tutorial can be found here.

3.7 Rotating the assembly image

Sometimes it makes sense to rotate the assembly image to give the reader a better view of where the parts are added. This can be done using the ROTSTEP command, which takes the following basic form:

0 LPUB ROTSTEP X Y Z REL

The X, Y & Z are the dimensional axes of the 3D assembly image. You can change the rotation of the assembly image by specifiying the values for how far (in degrees) the assembly should rotate around each axis.

In the following example, the two white plates have just been added to create a window sill, and some flowers will be added to the window sill in a subsequent step.

Rotating this view by 90 degrees on the Y-axis will allow us to view the window from the outside. This can be done as follows:

1. Add the ROTSTEP command shown below.

2. Click the "Redraw" button to refresh the page.

0 STEP
0 LPUB ROTSTEP 0 90 0 REL
1 ... (parts for the step)
0 STEP

See here for the result.

Once a rotation has been set, it will apply to all subsequent steps. You can set the view back to the original orientation by adding the following code to the step where you need the original orientation to be shown:

0 LPUB ROTSTEP 0 0 0 REL

In the above example, the view is returned back to the original orientation once the window is completed, and all subsequent steps will now be in that original orientation. This is shown here.

Flipping an image so that the underside is shown can be done by setting the X or Z value to 180 degrees, as follows:

0 LPUB ROTSTEP 180 0 0 REL

or

0 LPUB ROTSTEP 0 0 180 REL

In this example, the last image in the sub model has been rotated by 180 degrees around the X-axis to show where the feet (i.e. 1x1 round plates) of the lounge chair should go.

There is no need to reset the view back to the original orientation in this instance as this is the last step in the submodel. The next step will be in the same orientation that was applied before the submodel was started.

Hints:

1. The X, Y and Z values can be positive or negative. For example, a value of +90 degrees will give a quarter turn in one direction, while a value of -90 degrees will give a quarter turn in the opposite direction.
   
2. Visualising the axes around the model helps to determine which axis (or axes) you should target to get the right orientation, as illustrated here. (Although I tend to use trial and error!)
   

[Kristel]

4. Grouped Steps and Submodels

4.1 Grouped Steps

Grouped steps are simply two or more steps shown on the same page. To create a grouped set of steps :

1. Right-click on the page to bring up the pop-up menu.
   
2. Select "Add Next Step".
   
3. Repeat steps 1 & 2 until you have all the steps you want on the page.
   

You can use dividers to create multiple columns or rows of steps, thereby being able have a greater number of steps on the page.

In this example, I wanted to have five steps showing on the one page and the page is in landscape orientation. Only four steps were able to fit on the page, so I added a divider after the third step (by right-clicking on the assembly image for Step 3 and selecting "Add Divider After Step"), and then adding the fifth step.

Right-clicking on the grouped steps also gives you the option to "Display as Rows" or "Displays as Columns". The difference is shown in the same example.

4.2 Callouts

Submodels (shown with a light yellow background as the default formatting) can be formatted in the same way as grouped steps. A small submodel can also be converted to a callout by right-clicking on the page and selecting "Convert to Callout".

In this example, LPub created the callout as a series of steps in a column on the right hand side. You can move the location of the callout by right-clicking on it and selecting "Move this Callout".

The "Left:Center" option was chosen in this example, but that still looked a bit wrong, so I moved it to the "Top:Center" and then opted to "Display as Rows". Looks much better, I think.

Hints:

• If there are a number of callouts in the one set of instructions, it is recommended that you work through the callouts in sequential order, starting with the first one. Formatting done on one callout can affect the formatting of subsequent callouts. For example, if you change the location of a callout, the location of any callouts that follow also tend to be moved.
  
• I generally place the callout on the outside of the assembly image (by selecting one of the outmost options in the placement dialog box), as placing it on the assembly image can make the instructions look crowded. However, this can be a useful option if you have limited room on the page.
  
• You can move the callout by clicking on it, holding down the mouse button and dragging the callout. However, this is recommended for small changes in location as big moves (for example, from the top of the page to the bottom of the page) can have unexpected consequences, such as the main assembly image moving off the screen.
  

A callout can also be used to point out where a specific part needs to be placed. In the next example, the only part that is included in the submodel is a tap and it has been converted to a callout. You can move the parts list for the submodel out of the callout by right-clicking the callout and selecting "No Parts List per Step".

Note: LPub treats the first model in a file as the main model and will only produce steps for this model and any submodels that are referenced in that first model. If you have two models in a file and want to create instructions for both in the same document, you will need to add a step at the end of the first model and then reference the second model. If you set the submodel background colour to the same colour as the main model, it will simply look like instructions for another model.

4.3 Using Buffer Exchange

Sometimes it's necessary to highlight or show more clearly where to place parts or submodels in the main model, as shown in the following screenshots.

Images courtesy of Alasdair Ryan

A buffer exchange can be used to create these types of instructions and allows you to add temporary arrows, move pieces and change the colour of parts to define them better.

Buffer exchange code is added in MLCad and is therefore not covered in this guide. However, Alasdair Ryan has written a comprehensive tutorial on using buffer exchanges. His tutorial can be found here.

[Kristel]

5. Bill of Materials

You can add a list of all parts at the back of the instructions as follows:

1. Go to the last step in the instructions.

2. Add a page by selecting "Append Page" in the "Edit" menu.

3. Selecting "Add Bill of Materials, which is also under the "Edit" menu.

Unless you have a small model with a small number of different types of parts, the BOM created by LPub will more than likely look something that like the following screenshot, with parts going off the page and sorted (mostly) by type of part.

There are several things that can be done to make the BOM fit neatly on the page. The first is to sort the parts by size, which is done by adding the last line of code in the code box below (the first two lines are added automatically through steps 2 & 3 above) and then clicking the "Redraw" icon.

0 !LPUB INSERT PAGE
0 !LPUB INSERT BOM
0 !LPUB BOM SORT FALSE

This will sort the parts by size, meaning you can fit more columns of parts on the page, as shown here.

The other things you can do to make the BOM fit onto the page is to change the scale of the parts, reduce the font size for the part quantities and change the size of the BOM bounding box. You can change the shape of the bounding box by clicking on the BOM to show the bounding box little black square, grabbing the square and moving it up or down to create more or fewer columns in the BOM.

Other formatting parameters can be changed through selecting "Bill of Materials Setup" under the "Configuration" menu, as shown below.

It can be difficult to produce a readable BOM for models with a large number of different parts. You can only reduce the scale and font size so much before it becomes difficult to see the parts. In these instances, it is often simpler and better to prepare a parts list in spreadsheet or xml format.

[Kristel]

6. Exporting the Instructions

This section covers the options for exporting the instructions, which are essentially as PDF or as a series of images. If you choose to export as a PDF, you may want to add a cover page first.

6.1 Adding a cover page

LPUB has the functionality to add text and images to a page. However, I have found it easiest to prepare a cover page in a separate program (e.g. Keynote, Powerpoint, Inkscape, Photoshop, CorelDraw, etc), exporting that as a JPG and then using the JPG image as the cover.

You can add a cover page at the beginning of the instructions, as follows:

• Insert a blank page by choosing "Insert Cover Page" from the Edit menu.
  
• Navigate to the front page.
  
• Add an image by choosing "Add Image", which is also in the Edit menu.
  
• Reposition and resize the image as required:
  
  • To resize, click on the image to bring up the bounding box with the little black squares on each corner. You can then change the size by clicking on and dragging one of the black squares, as shown here.
    
  • To move, click on the image, hold the mouse button down and drag the image to the required location on the page.
    

For a small model with a small parts list, I often include the parts list on the front cover, as shown in the same example. The BOM is added to the front page by selecting "Add Bill of Materials" from the Edit menu. The BOM can be formatted, resized and moved as shown in Section 5 above.

6.2 Exporting to PDF

Once you're happy with the layout of the individual pages, you can print the instructions to PDF by clicking on the PDF icon.

You can also find the "Print to File" option under the "File" menu.

6.3 Exporting as a series of images

The other option is to export the steps as a series of images, with the options provided by LPub being PNG, JPEG or Bitmap images. The JPEG images are lighter weight than PNGs, and can significantly reduce the overall file size without sacrificing quality.

Using this option results in a series of images that you will then need to collate into a PDF or other format for sharing and reading. While this requires more effort, I usually prefer this option as it gives greater flexibility over editing and layout of the final product.

The end!

[Kristel]

Frequently Asked Questions

[Kristel]

Reserved for Future Use

[Kristel]

Reserved for Future Use

[Calabar]

Now we can start the discussion.

[Classicsmiley]

Thanks for putting this together. I've been using LPub since you had to add the meta commands manually, but I'm still looking forward to learning new things!

[bats]

LPub BOM from SR 3D Builder

I have recently completed a project in SR 3D Builder and MLCAD. When I opened the file in LPub, the NXT was split up into several different parts in the BOM. Is there a way to show the NXT as one complete piece in the BOM?

Thanks,
Nathan

Edited June 30, 2013 by Calabar
: Post moved in the proper topic.

[Alasdair Ryan]

Bats do you mean NXT cable?

[Lipko]

Similar thread:

http://www.eurobrick...showtopic=83590

You just have to replace PLI with BOM I believe.

Edited July 1, 2013 by Lipko

[legolijntje]

No, that's not a problem of SR3D Builder. It's because the part (in this case an nxt) is made of subparts. You can read more about this here (but maybe there are more solutions).

I don't have much experience with this either...

[bats]

I figured it out. What I did is I took the subparts that made up the NXT and made them into a submodel in MLCAD. Then I added that submodel to the main model and ghosted it. Then I added a normal NXT from MLCAD and put it in the same exact position as the submodel so it looks like there's only one piece. When I opened up the file in LPub I just clicked 'Ignore this Submodel' for the NXT submodel. It worked after that. The NXT was one complete piece and the subparts of the NXT were ghosted. Thanks for all your help.

[bats]

Now I have a new problem! Some of the pieces I used were in a buffer exchange. These pieces are shown in the BOM in LPub with a 2x next to them. The problem is that I only use those pieces once! For example it says I have two motors, but I only have one. The motor is in a submodel and then added into the main model with a buffer exchange. I think I must have done something wrong during that process. It happened to several pieces though. When I go to the step they are added in, it says you only need one of them in the PLI like it should. Why does it show 2x in the BOM if I only have one of them?

[bats]

Now that I looked at it closer it appears that it doubled all the pieces for mainly one specific submodel. It also doubled three other pieces. They were all in buffer exchanges. I think that is the problem.

[Kristel]

Now that I looked at it closer it appears that it doubled all the pieces for mainly one specific submodel. It also doubled three other pieces. They were all in buffer exchanges. I think that is the problem.

Hi Bats. I don't know a lot about buffer exchanges as I don't use them. Hopefully, Alasdair or others with more experience in this area will be able to help you.

[Alasdair Ryan]

Hello bats the easiest way to try and solve the issue would be if you could you share the cad file or or cut and past the relevant MLcad code.

Have you made sure you have checked the buffer commands to make sure you have done every thing correctly?

There is a brief guide on buffer exchange on my blog,maybe you should look at that to see if you can find any errors.

Buffer Exchange guide on my blog.

[bats]

Here is the code for the one submodel that seems to be the major problem:

STEP
STORE A
PART-SUBMODEL
ARROW
ARROW
ARROW
ARROW
ARROW
STEP
RETRIEVE A
PART-SUBMODEL
STEP

[Philo]

That's indeed the typical code that sometimes create problem. Often it's OK, but sometimes submodel instruction is duplicated (or parts appear twice in PLI/BOM). So far I have not been able to see what creates this behaviour. What I do in this case is to surround the second model instance with part ignore statements:

STEP
STORE A
PART-SUBMODEL
ARROW
ARROW
ARROW
ARROW
ARROW
STEP
RETRIEVE A
0 !LPUB PART BEGIN IGN
PART-SUBMODEL
0 !LPUB PART END
STEP