Yes is the default.
Yes will give you the safety blocks in the beginning and at the end of the program. It will also provide the tool calls for each cut. Setting this feature to No will not provide any safety blocks or tool changes, but just the XYZ motions of the cut.
For example, all of the cycles to be cut by the same spindles at the same time can be grouped into a Sequence without Start and End Codes (by selecting No). Each group of Sequences can then be grouped again into a final Sequence with Start and End codes.
Here is the code for a sequence with Start and End Codes set to NO:
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:1
N1G41D01G01Z-.75F200.
N2G03X3.Y-.249I-.5F500.
N3G01X.5
N4G02X-.249Y.5J.749
N5G01Y3.5
N6G02X.5Y4.249I.749
N7G01X5.5
N8G02X6.249Y3.5J-.749
N9G01Y.5
N10G02X5.5Y-.249I-.749
N11G01X3.
N12X2.5F500.
N13G03X2.Y-.749J-.5
N14S18000
N15G00G43H0Z.25
N16G40G00Y-1.024
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Here is the same tool path with the Start and End Codes set to YES. The code in red is what Start and End Code added to the program.
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:1 (START AND END CODES ON)
N1G00G17G20G28G40G80G91Z0M5
N2G90
N3G52X0Y0Z0
N4G08P1
N5M08
N6(ROUTER-BIT .5 DIA.)
N7G28G91Z0M05
N8G90T2001M06
N9T102
N10M03S18000
N11G00G17G55X3.5Y-1.024
N12G00G43H1Z.25
N13G41D01G01Y-.749F200.
N14Z-.75
N15G03X3.Y-.249I-.5F500.
N16G01X.5
N17G02X-.249Y.5J.749
N18G01Y3.5
N19G02X.5Y4.249I.749
N20G01X5.5
N21G02X6.249Y3.5J-.749
N22G01Y.5
N23G02X5.5Y-.249I-.749
N24G01X3.
N25X2.5F500.
N26G03X2.Y-.749J-.5
N27G00Z.25
N28G40G00Y-1.024
N29G28G91Z0M5
N30G28G91X0M09
N31G90
N32G52X0Y0Z0
N33G08P0
N34M30
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