The SPLayIso command is similar to the LAYISO command, except that when certain Civil-3D entities are selected, all layers involved in displaying the entity will remain visible. Also works to isolate entire XREFs, or individual layers inside of XREFs.
Type SPLayIso at the command line, and select objects on the layers you wish to isolate.
Instead of selecting an item at the prompt, you may also key in the name of a Layer. Key in "NA" at the prompt for the "Name" option, then type in a layer name. You may use an asterisk (*) as a wildcard, to indicate multiple layers. For example, if you enter V-*-PH01 as a layer name, this command will isolate all layers with names that start with "V-" and end with "-PH01".
Unfortunately, at this time, the SPLayIso command does not work through XREFs. When selecting items inside an XREF, it will still isolate the overall layer for the C3D object, similar to the behavior of the default LAYISO command. Also, the command currently only works on the following Civil-3D elements:
Primary Parcel Area Label
Parcel Segment Labels (not available in 2008 version)
General Line/Curve Labels (not available in 2008 version)
In addition, the SPLayIso command also works a bit differently than the default LAYISO command when selecting an XREF. When selecting an XREF, all layers inside the XREF remain on, so the entire XREF remains visible. Or, you may type "NE" for the "Nested" option to select an item inside an XREF. Blocks behave in a similar fashion, except if the item inside the block is on Layer 0, the overall layer of the block is selected instead.
Parcel Segment Labels and General Line/Curve Labels (not available in 2008 version)
The way these labels are implemented in the API, each label may have two styles attached to it. One style is for Line Segments, and the other is for Curve Segments. Even though the label only displays one or the other, it always has both a Line and a Curve style attached to it. This can be seen by selecting the label and looking at its properties in the Properties Palette.
If both the Line style and the Curve style are set to display on two different layers, the SPLayIso command will keep BOTH layers turned on. This may create unexpected results when the two styles are accidentally set differently.
Similar to the LAYFRZ command, except will freeze (or vpfreeze, in paperspace) the "apparent" layer of certain Civil-3D entities.
Similar to the LAYMCH (Layer Match) command, except objects are changed to match the "apparent" layer of certain Civil-3D entities.
Similar to the LAYOFF (Layer Off) command, except will turn off the "apparent" layer of certain Civil-3D entities.