Several little questions about VHDL and its simulation wave

[Altera_Forum]

I am working on VHDL,I have got some questions. 

1.what does the wave form ,that is just a vertical line and lasted for no-time,mean? In my work that signals still worked in sequencial case,seeming not to consider the tsu and th parameters.That's confusing.   2.Does the output signal affect its inner signals? The output signal was just assigned somewhere in the codes,but not control anything.In my work, inner signals wave form would change if I change the place of assignment of output signal.That's what I cannot understand.   3.If I use this type of program shown below,the action to the conctrol signal should happen in the next clock edge.,not the current edge,am I right? ...... 1:process(...) begin control<='0'...--reset control signal ......control<='1';--assign it somewhere in clock edge end process; 2:process(...)begin if rising_edge(clk) and control='1' then ...--action   Thanks for your attention.

[Altera_Forum]

--- Quote Start ---   3.If I use this type of program shown below,the action to the conctrol signal should happen in the next clock edge.,not the current edge,am I right? ...... 1:process(...) begin control<='0'...--reset control signal ......control<='1';--assign it somewhere in clock edge end process; 2:process(...)begin if rising_edge(clk) and control='1' then ...--action    --- Quote End ---    Yes, the action to the conctrol signal should happen in the next clock edge

[Altera_Forum]

Thanks for relpy.We are considering similar,but what I see in the simulation is that so long as the rising edge of the control signal the action to it will take effect.I can't make head or tail.

[Altera_Forum]

Postpoint:I lost some points.Half of time for the control signal take effect in the rising edge of current clock, while the other half lasted for a period doing nothing. 

Sorry for that.

[Altera_Forum]

I havn't got any explain and solution on the ultrathin signal wave.Now I want to know that if I use buffer mode as ouput type to watch the inner signals,what will result in? In my code,it sounds different when apply the buffer mode.So anybody explains why?