Index: generic/predefined.h
===================================================================
diff -u -rf0f0b5422a37c8d05f6b835de37fda6bb7347dfd -rdaafc0f0261f6b47a01c7cc8975acdd66f91f360
--- generic/predefined.h	(.../predefined.h)	(revision f0f0b5422a37c8d05f6b835de37fda6bb7347dfd)
+++ generic/predefined.h	(.../predefined.h)	(revision daafc0f0261f6b47a01c7cc8975acdd66f91f360)
@@ -21,7 +21,7 @@
 "namespace import ::nx::core::next ::nx::core::self\n"
 "foreach cmd [info command ::nx::core::cmd::Object::*] {\n"
 "set cmdName [namespace tail $cmd]\n"
-"if {$cmdName in [list \"instvar\"]} continue\n"
+"if {$cmdName in [list \"exists\" \"instvar\"]} continue\n"
 "::nx::core::alias Object $cmdName $cmd}\n"
 "::nx::core::alias Object eval -nonleaf ::eval\n"
 "foreach cmd [info command ::nx::core::cmd::Class::*] {\n"
@@ -160,7 +160,8 @@
 "if {![::nx::core::objectproperty ${slotParent} object]} {\n"
 "::nx::Object create ${slotParent}}\n"
 "return ${slotParent}::$name}\n"
-"::nx::MetaSlot method createFromParameterSyntax {target -per-object:switch\n"
+"::nx::MetaSlot method createFromParameterSyntax {\n"
+"target -per-object:switch\n"
 "{-initblock \"\"}\n"
 "value default:optional} {\n"
 "set opts [list]\n"
@@ -207,7 +208,7 @@
 "if {[llength $att]>1} {foreach {att default} $att break}\n"
 "if {[info exists default]} {\n"
 "foreach i [::nx::core::cmd::ClassInfo::instances $class] {\n"
-"if {![$i exists $att]} {\n"
+"if {![::nx::core::existsvar $i $att]} {\n"
 "if {[string match {*\\[*\\]*} $default]} {\n"
 "set value [::nx::core::dispatch $i -objscope ::eval subst $default]} else {\n"
 "set value $default}\n"
@@ -232,7 +233,7 @@
 "::nx::ObjectParameterSlot public method add {obj prop value {pos 0}} {\n"
 "if {![set :multivalued]} {\n"
 "error \"Property $prop of [set :domain]->$obj ist not multivalued\"}\n"
-"if {[$obj exists $prop]} {\n"
+"if {[::nx::core::existsvar $obj $prop]} {\n"
 "::nx::core::setvar $obj $prop [linsert [::nx::core::setvar $obj $prop] $pos $value]} else {\n"
 "::nx::core::setvar $obj $prop [list $value]}}\n"
 "::nx::ObjectParameterSlot public method delete {-nocomplain:switch obj prop value} {\n"
@@ -382,6 +383,7 @@
 "::nx::core::register_system_slots ::nx\n"
 "proc ::nx::core::register_system_slots {} {}\n"
 "::nx::MetaSlot __invalidateobjectparameter\n"
+"# @param incremental Allows for using the fine-grained modification (i.e., setting) of the managed variable {e.g., through an incremental {{{add}}})\n"
 "::nx::MetaSlot create ::nx::Attribute -superclass ::nx::ObjectParameterSlot\n"
 "createBootstrapAttributeSlots ::nx::Attribute {\n"
 "{value_check once}\n"
@@ -400,9 +402,9 @@
 "::nx::Attribute protected method init {} {\n"
 "::nx::core::next ;# do first ordinary slot initialization\n"
 "set __initcmd \"\"\n"
-"if {[:exists default]} {} elseif [:exists initcmd] {\n"
+"if {[info exists :default]} {} elseif [info exists :initcmd] {\n"
 "append __initcmd \":trace add variable [list ${:name}] read \\\n"
-"\\[list [::nx::core::current object] __default_from_cmd \\[::nx::core::current object\\] [list [set :initcmd]]\\]\\n\"} elseif [:exists valuecmd] {\n"
+"\\[list [::nx::core::current object] __default_from_cmd \\[::nx::core::current object\\] [list [set :initcmd]]\\]\\n\"} elseif [info exists :valuecmd] {\n"
 "append __initcmd \":trace add variable [list ${:name}] read \\\n"
 "\\[list [::nx::core::current object] __value_from_cmd \\[::nx::core::current object\\] [list [set :valuecmd]]\\]\"}\n"
 "array set \"\" [:toParameterSyntax ${:name}]\n"
@@ -414,7 +416,7 @@
 "::nx::core::next}} else {\n"
 ":method assign [list obj var value:$(mparam),slot=[::nx::core::current object]] {\n"
 "::nx::core::setvar $obj $var $value}}}\n"
-"if {[:exists valuechangedcmd]} {\n"
+"if {[info exists :valuechangedcmd]} {\n"
 "append __initcmd \":trace add variable [list ${:name}] write \\\n"
 "\\[list [::nx::core::current object] __value_changed_cmd \\[::nx::core::current object\\] [list [set :valuechangedcmd]]\\]\"}\n"
 "if {$__initcmd ne \"\"} {\n"