View source for RPC HELP RPC Limits Max number of parameters

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<h2>Maximum Number of Parameters</h2>

The remote procedure calls (RPCs) become M DO procedures on the VistA M Server. Since RPCs are communicated to the VistA M Server through a message mechanism, additional information is included with the message.

Parameters are processed as PASCAL short strings with a maximum of 255 characters. Each parameter is encoded with a three-character length plus a type character. Therefore, every parameter occupies length (parameter) + four. The maximum transmission at this time is 240 characters, since additional header information is present with every RPC.
	
A theoretical maximum, where every parameter was length 1 would give number of parameters = 240/5 or 48 parameters. A single parameter (e.g., a long string) could not exceed 240 - 4, or 236 characters. Future support will be based on the PASCAL 32-bit string, which can, theoretically, reach 2 GB. Limitations on the VistA M Server will still limit this to far less, however.